NATIONAL CENTER FOR HEALTH STATISTICS

Vital and Health Statistics

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Statistical Methodology of the

National Immunization Survey,

2005–2014

Programs and Collection Procedures

Series 1, Number 61 December 2017
Copyright information

All material appearing in this report is in the public domain and may be 

reproduced or copied without permission; citation as to source, however, is 

appreciated.

Suggested citation

Wolter KM, Smith PJ, Khare M, et al. Statistical methodology of the National 

Immunization Survey, 2005–2014. National Center for Health Statistics. Vital and 

Health Statistics 1(61). 2017.

Library of Congress Cataloging-in-Publication Data

Names: National Center for Health Statistics (U.S.), issuing body.

Title: Statistical methodology of the National Immunization Survey, 2005-2014.

Other titles: Vital and health statistics. Ser. 1, Programs and collection 

 procedures ; no. 61. | DHHS publication ; no. 2018-1337. 0276-4733

Description: Hyattsville, Maryland : U.S. Department of Health and Human 

 Services, Centers for Disease Control and Prevention, National Center for 

 Health Statistics, December 2017. | Series: Vital and health statistics, 

 series 1, programs and collection procedures ; number 61 | Series: DHHS 

 pub ; number 2018-1337 | Includes bibliographical references.

Identifiers: LCCN 2017043643| ISBN 9780840606846 (pbk.) | ISBN 0840606842 

 (pbk.)

Subjects: | MESH: National Immunization Survey (U.S.). | Immunization | 

 Health Surveys--methods | Statistics as Topic | Data Collection--methods | 

 United States

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Printed on acid-free paper.
Vital and Health Statistics

Series 1, Number 61

Statistical Methodology of the

National Immunization Survey,

2005–2014

Programs and Collection Procedures

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Hyattsville, Maryland

December 2017

DHHS Publication No. (PHS) 2018–1337
National Center for Health Statistics

Charles J. Rothwell, M.S., M.B.A., Director

Jennifer H. Madans, Ph.D., Associate Director for Science

Division of Research and Methodology

Jennifer D. Parker, Ph.D., Acting Director

Donald J. Malec, Ph.D., Associate Director for Science
iii

Contents 

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

NIS–Child . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

NIS–Teen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Outline of the Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Sampling Design, Questionnaire, and Response Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Sampling Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

2013 Household-survey Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

2013 Household Questionnaire. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

2013 Provider Record Check Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Response Rates and Key Monitoring Statistics, 2005–2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Representation of the Target Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Estimation Methodology for NIS–Child. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Imputation of Weighting Variables, 2005–2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2005–2010 Single-frame Estimation Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2011–2014 Dual-frame Estimation Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Ratio Estimator of the Vaccination Coverage Rate and the Taylor Series Estimator of Its Variance . . . . . . . . . . . . . . . 24

NIS–Teen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Sample Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

NIS–Teen Survey Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Response Rates and Key Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Trends in Key Indicators for NIS–Teen, 2006–2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Estimation Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Topical Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

NIS–Child Knowledge, Attitudes, and Practices Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Concurrent Modules 2001–2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Vaccine Shortage and Vaccine Safety Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Influenza Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Revisions to HIM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

HIM for NIS–Teen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Socioeconomic Status Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

NIS–Child Parental Concerns Module and NIS–Teen Parental Attitudes Module. . . . . . . . . . . . . . . . . . . . . . . . . 33

Quality Assurance and Data Dissemination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Quality Assurance Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Confidentiality and Disclosure Avoidance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Data Dissemination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
iv

Evaluation of NIS Estimates and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Evaluation of NIS–Child Data Quality Using IIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Assessment of Representativeness of Alternative Sampling Frames for NIS–Child. . . . . . . . . . . . . . . . . . . . . . . . 41

Comparing NIS–Child Vaccination Coverage Rates With Those Provided by NHIS-PRC . . . . . . . . . . . . . . . . . . . . 44

Assessment of TSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Other Surveys in the NIS Family of Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

NIS–Adult, 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

NHFS, 2009. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

NIS–Kindergarten, 2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

NIS–Flu, 2010–2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Appendix I. Recommended Immunization Schedules for Persons Aged 0 Through 18 Years: United States, 2014 . . . . . . . . . 84

Appendix II. Definitions of Terms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Detailed Tables

1. Vaccines monitored by National Immunization Survey–Child in 2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

2. Vaccines monitored by National Immunization Survey–Teen in 2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

3. Major changes since 2005 in the protocol of the National Immunization Survey–

Child random-digit-dialing sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

4. Population of children aged 19–35 months on July 1, 2013, for the 56 core estimation areas in

National Immunization Survey–Child, by telephone status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

5. Annual sample sizes and actual completed interviews from National Immunization Survey–Child, 

by estimation area: Landline random-digit-dialing sample, 2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

6. Annual sample sizes and actual completed interviews from National Immunization Survey–Child, 

by estimation area: Cell-phone random-digit-dialing sample, 2013. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

7. Content of the household interview questionnaire from National Immunization Survey–Child, 2013 . . . . . . . . . . . . 62

8. Key monitoring statistics for National Immunization Survey–Child: 

Landline random-digit-dialing sample excluding U.S. territories, 2005–2014 . . . . . . . . . . . . . . . . . . . . . . . . 63

9. Key monitoring statistics for National Immunization Survey–Child: 

Cell-phone random digit-dialing sample excluding U.S. territories, 2011–2014 . . . . . . . . . . . . . . . . . . . . . . . 64

10. Annual household response rates for National Immunization Survey–Child: 

Combined landline and cell-phone random-digit-dialing samples excluding U.S. territories, 2011–2014 . . . . . . . . . . 64

11. Item nonresponse rates for demographic variables subject to imputation in 

National Immunization Survey–Child: Landline random-digit-dialing sample, 2005–2014 . . . . . . . . . . . . . . . . . 65

12. Item nonresponse rates for demographic variables subject to imputation in 

National Immunization Survey–Child: Cell-phone random-digit-dialing sample, 2011–2014 . . . . . . . . . . . . . . . . 65

13. Candidate predictor variables for fitting the response propensity model for whether a child has 

adequate provider data for National Immunization Survey–Child: 2005–2010, excluding U.S. territories . . . . . . . . . 66

14. Sample sizes and coefficient of variation of weights in National Immunization Survey–Child: 

2005–2014, excluding U.S. territories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

15. Candidate predictor variables for fitting the response propensity model for whether a child has 

adequate provider data for National Immunization Survey–Child: 2011–2014, excluding U.S. territories . . . . . . . . . 68

16. Key monitoring statistics for National Immunization Survey–Teen: 

Landline random-digit-dialing sample excluding U.S. territories, 2006–2014 . . . . . . . . . . . . . . . . . . . . . . . . 70

17. Key monitoring statistics for National Immunization Survey–Teen: 

Cell-phone random-digit-dialing sample excluding U.S. territories: 2011–2014 . . . . . . . . . . . . . . . . . . . . . . . 71

18. Annual household response rates for National Immunization Survey–Teen: 

Combined landline and cell-phone random-digit-dialing samples excluding U.S. territories, 2011–2014 . . . . . . . . . . 71

19. Percentage of adolescents in the population within estimation area for 

National Immunization Survey–Teen, by telephone status, 2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

20. Topical modules conducted as part of National Immunization Survey–Child and –Teen. . . . . . . . . . . . . . . . . . . 74

21. Data-processing steps for National Immunization Survey–Child and –Teen, 2005–2014 . . . . . . . . . . . . . . . . . . 75
v

22. Edit limits for vaccination date that trigger a matching sheet review: 

National Immunization Survey–Child and –Teen, 2014. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

23. Quality assurance in imputation for National Immunization Survey–Child and –Teen, 2005–2014 . . . . . . . . . . . . . 77

24. Quality assurance in weighting for National Immunization Survey–Child and –Teen, 2005–2014 . . . . . . . . . . . . . 77

25. Percentage of children in National Immunization Survey–Child also included in 

19 immunization information systems, 2008–2011 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

26. Minimum and maximum differences in vaccination coverage rates between National Immunization Survey–Child, 

19 immunization information systems, and synthesized National Immunization Survey and 

immunization information systems, 2008–2011. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

27. Percentage of estimated vaccination coverage rates and corresponding 95% confidence intervals for 

children aged 19–35 months: National Immunization Survey–Child and address-based sample pilot, 2009. . . . . . . . . 79

28. Vaccination coverage rates for children aged 19–35 months for each recommended childhood vaccine, by survey:

National Immunization Survey–American Community Survey and 

Florida National Immunization Survey–Child, 2009 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

29. Differences in vaccination coverage rates for children aged 19–35 months between 

National Immunization Survey–Child and immunization information systems samples:

Quarter 1–Quarter 2, 2008 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

30. Comparison of response rates in National Immunization Survey–Child and 

National Health Interview Survey: 2009–2013, excluding U.S. territories . . . . . . . . . . . . . . . . . . . . . . . . . . 80

31. National vaccination coverage rates for children aged 19–35 months in 

National Immunization Survey–Child and National Health Interview Survey–Provider Record Check: 

Quarter 1–Quarter 4, 2009 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

32. National vaccination coverage rates for children aged 19–35 months in 

National Immunization Survey–Child and National Health Interview Survey–Provider Record Check: 

Quarter 1–Quarter 4, 2010 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

33. Key indicators for National Immunization Survey–Adult: 2007, excluding U.S. territories . . . . . . . . . . . . . . . . . 82

34. Key indicators for National H1N1 Flu Survey at end of influenza season: 2009, excluding U.S. territories . . . . . . . . . 82

35. Key indicators for National Immunization Survey–Kindergarten: 2013, excluding U.S. territories . . . . . . . . . . . . . 82

36. Key indicators for National Immunization Survey–Flu Child Influenza Module at end of 

influenza season: 2010–2014, excluding U.S. territories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Text Figures

1. Percentages of adults and children living in households with only wireless telephone service: 

United States, 2003–2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

2. Percentage of children aged 19–35 months in the population, by telephone status within estimation area, 2013 . . . . . . .6

3. Trends in key indicators from household and provider data collections for National Immunization Survey–Child:

Landline random-digit-dialing sample excluding U.S. territories, 2005–2014 . . . . . . . . . . . . . . . . . . . . . . . . 12

4. Trends in key indicators from household and provider data collections for National Immunization Survey–Child:

Cell-phone random-digit-dialing sample excluding U.S. territories, 2011–2014 . . . . . . . . . . . . . . . . . . . . . . . 13

5. Trends in percentages of children with two or more providers among children with adequate provider data, and 

children with one or more providers not reporting among children with adequate provider data and 

two or more providers, for National Immunization Survey–Child: 

Landline random-digit-dialing sample excluding U.S. territories, 2005–2014 . . . . . . . . . . . . . . . . . . . . . . . . 14

6. Trends in percentages of children with two or more providers among children with adequate provider data, and 

children with one or more providers not reporting among children with adequate provider data and 

two or more providers, for National Immunization Survey–Child:

Cell-phone random-digit-dialing sample excluding U.S. territories, 2011–2014 . . . . . . . . . . . . . . . . . . . . . . . 15

7. Weighting flowchart for National Immunization Survey–Child, 2005–2010 . . . . . . . . . . . . . . . . . . . . . . . . . 17

8. Weighting flowchart for National Immunization Survey–Child, 2011–2014 . . . . . . . . . . . . . . . . . . . . . . . . . 22

9. Trends in key indicators from household and provider data collections for National Immunization Survey–Teen: 

Landline random-digit-dialing sample excluding U.S. territories, 2011–2014 . . . . . . . . . . . . . . . . . . . . . . . . 27

10. Trends in key indicators from household and provider data collections for National Immunization Survey–Teen: 

Cell-phone random digit dialing sample excluding U.S. territories, 2006–2014 . . . . . . . . . . . . . . . . . . . . . . . 28

11. Trends in percentages of adolescents with two or more providers among adolescents with adequate provider data, and 

adolescents with one or more providers not reporting among adolescents with 

adequate provider data and two or more providers, for National Immunization Survey–Teen: 

Combined landline and cell-phone random-digit-dialing samples excluding U.S. territories, 2006–2014 . . . . . . . . . . 29
vi

12. Percentage of adolescents in the population, by telephone status within estimation area, 2013 . . . . . . . . . . . . . . . 31

13. Immunization history questionnaire keying error rates for National Immunization Survey–Child, 2005–2011 . . . . . . . 36

14. Immunization history questionnaire keying error rates for National Immunization Survey–Teen, 2006–2014 . . . . . . . 37

15. Trends in percentage of children with one or more changes to a vaccination among children with 

one or more valid immunization history questionnaires returned, by vaccine category, 2005–2014 . . . . . . . . . . . . . 38

16. Trends in percentage of adolescents with one or more changes to a vaccination among adolescents with 

one or more valid immunization history questionnaires returned, by vaccine category, 2006–2014 . . . . . . . . . . . . . 39

17. Mean total survey error for the 4:3:1:3:3:1 vaccination series and 1 or more MMR and 

4 or more DTaP vaccines, by survey year, 2009–2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

18. Mean total survey error for 1 or more Tdap and 1 or more meningococcal vaccines, and 

1 or more HPV vaccines for females, by survey year, 2009–2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Appendix Figure

Spectrum of telephone statuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
vii

Acknowledgments

The authors gratefully acknowledge 

the assistance of Nadarajasundaram 

Ganesh, Marilyn Ford, Jacquelyn George, 

Cindy Howes, Reiping Huang, Laura 

Lancheros, Robert Montgomery, Megha 

Ravanam, Kathleen Santos, Benjamin 

Skalland, and Wei Zeng, NORC at the 

University of Chicago; and Tammy 

Santibanez and Zhen Zhao, Centers for 

Disease Control and Prevention (CDC); 

in the preparation of this report. The 

authors appreciate the input of several 

CDC staff members who reviewed the 

report at various stages of development, 

including Laurie Elam-Evans, Stacie 

Greby, James A. Singleton, Shannon 

Stokley, Jennifer H. Madans, and Amy 

M. Branum.
Page 1 

Statistical Methodology of the 

National Immunization Survey, 

2005–2014

by Kirk M. Wolter, Ph.D., NORC at the University of Chicago; Philip 

J. Smith, Ph.D., National Center for Immunization and Respiratory 

Diseases (currently with Georgia State University, School of Music); 

Meena Khare, M.S., National Center for Health Statistics; Bess Welch, 

Ph.D., Kennon R. Copeland, Ph.D., Vicki J. Pineau, M.S., and Nicholas 

Davis, M.S., NORC at the University of Chicago

Introduction 

The history of surveillance of 

vaccination coverage in the United 

States (1) includes the 1921 Hagerstown 

Morbidity Study (2), the 1928–1931 

U.S. Morbidity Study (3), the 1936 

U.S. Public Health Service Study (1), 

and the 1943 national survey of public 

attitudes toward immunizations (4). A 

resurgence of polio in the early 1950s 

led to the United States Immunization 

Survey, which was conducted annually 

from 1957 through 1985 as a supplement 

to the Current Population Survey (5,6). 

After a hiatus in vaccination coverage 

assessment from 1986 through 1991 

and a resurgence of measles (7,8), the 

Childhood Immunization Initiative (9) 

was established in 1992 to improve the 

delivery of vaccines to children; reduce 

the cost of vaccines for parents; enhance 

awareness, partnerships, and community 

participation; improve vaccinations 

and their use; and monitor vaccination 

coverage rates and occurrences of 

disease. 

To fulfill the Childhood 

Immunization Initiative mandate to 

monitor vaccination coverage and track 

progress toward achieving its goals, 

National Immunization Survey–Child 

(NIS–Child) was implemented by the 

National Immunization Program 

(the agency changed its name to the 

National Center for Immunization and 

Respiratory Diseases [NCIRD] in 2006) 

in partnership with the National Center 

for Health Statistics (NCHS) starting in 

1994. NIS–Teen was launched in late 

2006. Beginning in 2015, the 

implementation of the National 

Immunization Surveys (NIS), the family 

of surveys that started with NIS–Child, 

was transferred entirely to NCIRD. 

The Centers for Disease Control and 

Prevention (CDC) has used estimates of 

vaccination coverage from NIS to 

monitor vaccine uptake to allocate 

resources to state and selected 

immunization programs, in accordance 

with Section 317 of the Public Health 

Services Act (10) to conduct authorized 

activities to increase vaccination 

coverage, identify under-vaccinated 

subpopulations, and conduct 

epidemiologic research to help increase 

vaccination coverage. CDC has used data 

from NIS to monitor Healthy People 

objectives for 2000 (https://www.cdc.

gov/nchs/data/statnt/statnt11.pdf), 2010 

(https://wonder.cdc.gov/data2010/

FOCUS.HTM), and 2020 (https://www.

healthypeople.gov/2020/topicsobjectives/topic/immunization-andinfectious-diseases). 

NIS–Child

From its beginning, the target 

population of NIS–Child has been 

children aged 19–35 months living in 

households in the United States. The 

official vaccination coverage estimates 

reported from NIS–Child are the 

proportions of children fully vaccinated 

with the number of doses according to 

Objectives

The National Immunization Survey 

(NIS) family of surveys includes 

NIS–Child, which monitors vaccination 

coverage for the U.S. population of 

children aged 19–35 months; NIS–

Teen, which monitors vaccination 

coverage for the U.S. population of 

adolescents aged 13–17; and NIS–Flu, 

which monitors influenza vaccination 

coverage for the U.S. population 

of children aged 6 months through 

17 years. This report describes the 

methods used in this family of surveys 

during the 2005–2014 period.

Methods

NIS–Child and NIS–Teen collect 

data throughout the year in two 

phases: a telephone survey to identify 

households with age-eligible children 

and adolescents, followed by a mail 

survey to vaccination providers to 

obtain vaccination histories for the 

children and adolescents for whom 

parental consent was obtained to 

contact providers. The household 

interview is conducted for all children 

aged 19–35 months in the household. 

A random subsample of the telephone 

numbers is selected for NIS–Teen, 

and following the household interview 

for children (if any), the NIS–Teen 

interview is conducted for one 

randomly selected adolescent in the 

household. NIS–Flu collects data 

throughout the influenza season 

(October–June) and combines the 

household responses to influenza 

vaccination questions from NIS–Child, 

NIS–Teen, and a short instrument 

administered for children aged 6–18 

months and 3–12 years screened 

in the same sample of telephone 

numbers.

Results 

During 2005–2014, NIS–Child 

and NIS–Teen conducted household 

interviews by telephone for 255,644 

children and 250,330 adolescents. 

From the 2010–2011 through the 

2014–2015 flu seasons, NIS–Flu 

obtained information on 559,788 

children.

Keywords: dual-frame design • survey 

weighting • vaccination coverage rates 

• total survey error

Abstract
Page 2  Series 1, No. 61

the recommended vaccination schedule 

(11,12). The recommended vaccines 

that were monitored in the 2014 NIS–

Child are presented in Table 1, and a 

copy of the recommended vaccination 

schedule for 2014, including the timing 

of the doses of each vaccine, is shown 

in Appendix I. (The recommended 

vaccination schedule can change over 

time. Visit the Advisory Committee on 

Immunization Practices website at: 

https://www.cdc.gov/vaccines/acip.) In 

addition to individual vaccines, interest 

in NIS–Child has focused on various 

vaccine series, ranging from the 4:3:1 

series (see Appendix II for definition) 

to the 4:3:1:H:3:1:3 (with routine Hib) 

series used to monitor progress toward a 

Healthy People 2020 objective. 

CDC publishes NIS–Child 

vaccination coverage estimates annually 

for the country, states, select cities, and 

U.S. territories (13,14). NCHS released 

annual microdata files to the public (15) 

(https://www.cdc.gov/vaccines/imzmanagers/nis/data-tables.html) from 1995 

through 2014.

The NIS–Child sample was designed 

to be large enough to produce precise 

estimates of vaccination coverage in 56 

geographic (or estimation) areas. These 

areas include 6 urban areas that receive 

Section 317 immunization grant funding 

directly from CDC (Bexar County, Tex.; 

City of Chicago; City of Houston; City of 

New York; the District of Columbia; and 

Philadelphia County, Pa.); 4 rest-of-state 

areas (rest of Illinois, rest of New York, 

rest of Pennsylvania, and rest of Texas); 

and the remaining 46 whole states. The 

design has been flexible with the capacity 

to be expanded to support precise 

estimation for additional local areas and 

U.S. affiliated jurisdictions; the additional 

areas have varied from year to year. 

By using very similar survey designs, 

questionnaires, data-collection protocols, 

and statistical estimation procedures in all 

areas and from year to year, NIS–Child 

was designed to produce vaccination 

statistics that are comparable across 

geographic areas and across time, with 

little or no bias attributable to changing 

methodology. 

NIS–Teen

Before 2005, vaccines were 

administered to adolescents on a “catch 

up” basis, meaning vaccinations were 

provided to teenagers who did not 

receive them at the recommended 

age. During 2005 and 2006, three new 

vaccines were licensed in the United 

States and recommended for adolescents, 

including meningococcal conjugate 

vaccine (MenACWY); tetanus toxoid, 

reduced diphtheria toxoid, and acellular 

pertussis vaccine (Tdap); and human 

papillomavirus vaccine (HPV) (16,17). 

In response, systematic surveillance of 

the vaccination status of U.S. teenagers 

was instituted through NIS–Teen, which 

was launched in Q4/2006 (in this report, 

Q4 signifies the fourth quarter [October, 

November, and December] of the year 

2006) and Q4/2007 as national samples 

and continuously starting in 2008 with 

state and selected local area samples 

(18). NIS–Teen’s target population is 

adolescents aged 13–17 living in U.S. 

households at the time of the interview. 

The official vaccination coverage 

estimates reported from NIS–Teen (19) 

are rates of being up to date (UTD) 

with respect to the numbers of doses of 

recommended and catch-up vaccines. 

Table 2 presents the recommended 

vaccines that were monitored in the 

2014 NIS–Teen, and the recommended 

immunization schedule for 2014 and 

the timing of these doses appears in 

Appendix I.

Starting in 2008, the NIS–Teen 

sample was designed to be large enough 

to support precise annual estimation of 

vaccination coverage rates for the same 

56 geographic areas used in the survey of 

children aged 19–35 months. It was also 

designed to support additional local areas 

and territories, although the additional 

areas may vary from year to year and 

may not be exactly the same additional 

areas used for the survey of children.

Outline of the Report

This NCHS Vital and Health 

Statistics Series 1 report describes the 

methodology used in the NIS family 

from 2005 through 2014. For brevity, 

this report illustrates survey outcomes 

for 1 year, using 2013 as the focal year. 

Previous NCHS reports (20,21) discussed 

the methodology used to obtain offical 

estimates of vaccination coverage 

between 1994 and 2002. During the 

period of the current report, NORC at the 

University of Chicago has been the datacollection contractor.

“Sampling Design, Questionnaire, 

and Response Rates” describes the 

sampling design of NIS–Child, the survey 

questionnaires, and the survey response 

rates. As in the 1994–2004 survey years, 

the 2005–2014 surveys are based on a 

two-phase sampling design in which the 

first phase of data collection involves a 

random-digit-dialing (RDD) telephone 

survey within each of its statistical 

sampling strata to identify households 

in which one or more age-eligible 

children (aged 19–35 months) reside. 

Among households with age-eligible 

children, an interview is conducted and 

sociodemographic data are collected 

about the children, the mother of the 

children, and the household. At the end of 

the telephone interview, the interviewers 

request consent to contact the vaccination 

providers of the age-eligible children 

and providers’ contact information. In 

the second phase of data collection, a 

mail survey is sent to the vaccination 

providers of the children identified in the 

first phase to collect provider-reported 

vaccination histories for the children for 

whom consent was obtained.

During the past decade, an increasing 

number of young families have foregone 

use of a home (or landline) telephone 

and opted to have only a cellular (also 

known as “cell”) phone. In this report, 

these families are classified as having 

a cell-phone-only (CPO) telephone 

status. This shift away from landline 

telephones is one of the biggest changes 

to the survey’s environment since the 

beginning of NIS–Child (22,23). This 

change has meant that an increasing 

number of children in the population are 

not included in a single-frame, landline 

RDD telephone survey. In response, 

CDC and NORC at the University 

of Chicago conducted considerable 

research to study potential bias arising 

from the under-representativeness of the 

landline RDD survey and to formulate 
Series 1, No. 61  Page 3 

methods of design and estimation to limit 

any sample-frame noncoverage bias. 

Beginning in Q4/2010 and continuing 

through 2014, NIS–Child has included 

not only the landline RDD sample but a 

nationally representative RDD sample of 

cell-phone numbers. Official vaccination 

statistics for 2010, however, were based 

only on the landline RDD sample. For 

2011 through 2014, official vaccination 

statistics were based on the combined 

dual-frame sample (24). 

The cell-phone samples used in 

2010 and 2011 were relatively small 

national samples. Beginning in 2012 and 

continuing through 2014, much larger 

samples of cell-phone subscribers were 

included to support estimation for the 

previously mentioned states, local areas, 

and territories, optimally allocating the 

survey resources to the landline and 

cell-phone RDD frames. This allocation 

minimized the cost of data-collection 

operations while achieving a specified 

constraint on the sampling variance of 

the estimated vaccination coverage rate 

within estimation areas (25). The growing 

under-representativeness of the landline 

RDD survey and its effects are described.

Methods of estimation for the 

2005–2014 NIS–Child are described 

in “Estimation Methodology for NIS–

Child.” This section traces the evolution 

of estimation methods used as the 

survey transitioned from a single-frame 

design, to a dual-frame design featuring 

a relatively small national cell-phone 

RDD sample, to a dual-frame design 

that included a large cell-phone RDD 

sample and optimum allocation of the 

overall survey resources between the two 

sampling frames.

“NIS–Teen” focuses on the 

methodology of the survey of 

adolescents, which is based on 

subsamples of the RDD samples of 

telephone numbers selected for NIS–

Child. NIS–Teen also screens for 

presence of age-eligible adolescents and 

conducts household interviews about the 

adolescents following completion of all 

NIS–Child interviewing for the 

household. The material in this section 

refers to earlier sections of the report 

whenever the NIS–Teen method is 

similar to the corresponding NIS–Child 

method, and otherwise describes any 

differences between the NIS–Child and 

NIS–Teen methods. For 2010 and prior 

years, the official vaccination statistics 

were based on the landline RDD samples; 

for 2011–2014, the official statistics were 

based on the combined dual-frame RDD 

samples (26).

Special questionnaires, which are 

administered either once or periodically, 

are discussed in “Topical Modules.” The 

topical modules administered as part 

of the NIS–Child household interviews 

included the Health Insurance Module, 

the Parental Concerns Module, and the 

Socioeconomic Status Module. The 

topical modules administered in NIS–

Teen included the Health Insurance 

Module and the Parental Attitudes 

Module. The Health Insurance Module 

has been administered annually as part of 

NIS–Child and NIS–Teen since 2006.

“Quality Assurance and Data 

Dissemination” is discussed next, 

followed by “Evaluation of NIS 

Estimates and Methods.” The former 

discusses the quality assurance 

procedures employed throughout all 

phases of the survey, including data 

collection, data processing, data delivery 

phases, and the final dissemination of 

NIS statistics to the public. “Evaluation 

of NIS Estimates and Methods” assesses 

nonsampling error in NIS–Child and 

NIS–Teen statistics, and it assesses the 

completeness of the vaccination histories 

reported by the providers in the second 

phase of the surveys, the bias due to 

nonresponse in the first- and secondphase interviews, and the total survey 

error (TSE) in NIS–Child and NIS–Teen.

“Other Surveys in the NIS Family 

of Surveys” describes other vaccination 

surveys within the broader NIS family 

conducted during the period of this 

report, including NIS–Adult, the 

National 2009 H1N1 Flu Survey, NIS–

Kindergarten, and the ongoing NIS–Flu. 

Sampling Design, 

Questionnaire, and 

Response Rates 

Introduction

NIS–Child uses two phases of 

data collection to obtain vaccination 

information for a large national 

probability sample of young children: 

an RDD telephone survey designed to 

identify households with children aged 

19–35 months, followed by a provider 

record check (PRC) survey, which 

obtains provider-reported vaccination 

histories for these children. Data from 

the PRC show the number of doses each 

child received from the 10 vaccines 

shown in Table 1. These counts are 

compared with the recommended number 

of doses (see Appendix I and 

https://www.cdc.gov/vaccines/schedules/

hcp/child-adolescent.html) to determine 

whether the child is UTD. These data, 

along with sampling weights and NIS–

Child survey design information, are used 

to obtain estimated vaccination coverage 

rates for the country, states, selected large 

metropolitan areas, and U.S. territories.

From its beginning in 1994, the 

household phase of NIS–Child relied on 

an RDD sampling frame that included 

only landline telephone numbers. 

As NIS–Child was implemented, the 

telephone system in the United States 

underwent a massive, fundamental 

change. By the mid-2000s, a growing 

percentage of U.S. households had 

dropped their landline telephone service 

in favor of keeping only cell-phone 

service. In addition, some people who 

intermittently or never had landline 

telephone service now had cell-phone 

service. 

The rapid growth of the CPO 

population has been well documented 

(22). Figure 1 shows trends in the 

percentages of U.S. adults and children 

living in CPO households over time. 

CPO adults made up less than 5% of the 

population of adults in 2003 but more 

than 44% of the population by 2014. 

More than 54% of children under age 18 

years lived in CPO households by 2014. 
Page 4  Series 1, No. 61

constraint within a single estimation area 

is given approximately by

where p = 0.5 is the assumed true 

vaccination coverage rate, and n is the 

number of effective completed 

interviews. To achieve the required 

precision, a minimum of 178 effective 

completed interviews must be obtained. 

Because official vaccination 

coverage rates refer to children 

and are based on provider-reported 

information, this precision requirement 

and the corresponding effective sample 

sizes refer to children with provider 

information sufficient to determine 

whether the child has received the 

recommended vaccines. Such children 

are said to have “adequate provider data” 

(APD); see Appendix II for the definition. 

Since 2005, the survey has been designed 

to achieve an effective sample size of 180 

APD children per estimation area. 

The target number of household 

These percentages increased with time.

Beginning in 2008, a cell-phone 

RDD sampling frame was evaluated for 

use in the NIS family of surveys (see 

“Assessment of Representativeness 

of Alternative Sampling Frames for 

NIS–Child”). In Q4/2010, a national 

cell-phone RDD sample was piloted in 

the household phase of NIS–Child (not 

used in producing the official vaccination 

coverage rates for 2010), and in all 

four quarters of 2011 there was a more 

complete implementation of a cell-phone 

RDD sample into NIS. In 2012 and in 

subsequent years, a full dual-frame RDD 

sample was used to produce NIS–Child 

estimates.

This section of the report summarizes 

the household and provider phases of 

NIS–Child data collection, focusing on 

descriptions of the major methodological 

changes implemented from 2005 

through 2014. First, an overview of the 

sample design is provided, including 

recent innovations made in response to 

the changing telephony in the United 

States. This is followed by a description 

of the household survey and the PRC. 

Next, response rates and key monitoring 

statistics over time are discussed. 

The final topic is the completeness of the 

survey’s sampling frames. 

Major changes from 2005 through 

2014 in the protocol of the household 

phase of NIS–Child are shown in

Table 3.

Sampling Design 

See references 27–29 for descriptions 

of the NIS–Child sample design for the 

period 1994–2004.

Precision constraint

The main objective of NIS–Child 

is to monitor vaccination coverage rates 

nationally and by estimation area. The 

samples must be large enough to achieve 

the required statistical precision within 

each area. The NIS–Child design requires 

that within each estimation area, the 

coefficient of variation (CV) of a 50% 

statistic for the domain of age-eligible 

children based on an annual sample be 

no more than 7.5%. Assuming a simple 

random sampling of age-eligible children 

from a single sampling frame, the CV 

Figure 1. Percentages of adults and children living in households with only wireless telephone service: United States, 2003–2014

 

SOURCE: NCHS, National Health Interview Survey. 

≤ 0.075

p (1 – p)

n

p

CV =
Series 1, No. 61  Page 5 

interviews per area can be calculated by 

multiplying the effective sample size of 

APD children by the estimated design 

effect (mainly to account for a weighting 

effect), and then dividing by an estimate 

of the adequacy rate. This rate is the 

percentage of children with completed 

household interviews for whom consent 

was given to contact providers who 

returned sufficient data to measure the 

child’s vaccination status. The result of 

this calculation, divided by an estimate 

of the average number of children per 

household, yields the required number 

of household interviews. The estimated 

rates and design effect used to make 

these calculations are prepared using 

NIS–Child data from prior time periods. 

Further, division of the number of 

household interviews by the interview 

completion rate, the age-eligibility 

rate, the screening completion rate, the 

working residential number (WRN) rate, 

and the resolution rate yields the target 

number of telephone numbers required 

to obtain the number of household 

interviews. In other words, the annual 

target number, say n', of telephone 

numbers is calculated as

n' =

nD

δAPD γCLD δINT δELG δSCR δWRN δRES

where n = 180 is the annual effective 

sample size of APD children,

D is the estimated design effect,

δAPD is the rate of children with APD,

γCLD is the average number of children 

per eligible household,

δINT is the household interview 

completion rate,

δELG is the age-eligibility rate among 

screened households,

δSCR is the screening completion rate,

δWRN is the WRN rate among resolved 

households, 

and

δRES is the resolution rate of the 

residential status of the released 

telephone numbers.

The household phase of NIS–Child 

uses independent quarterly samples of 

landline telephone numbers in each of 

the estimation areas. Each sample is 

about one-fourth of the annual sample 

size. The procedures for managing the 

quarterly landline RDD samples ensure 

that the interviews in each estimation 

area are spread evenly across the quarter. 

To maintain an even workload, telephone 

interviewing of each quarterly sample 

extends for about 19 weeks, including 

13 weeks within the calendar quarter 

and about 6 weeks beyond the end of the 

calendar quarter overlapping the next 

following quarter.

Within established cost constraints, 

the main goals of the NIS–Child 

household phase are to:

● Maintain an up-to-date sampling 

frame of telephone numbers

● Minimize the number of age-eligible 

children in the population who are 

excluded from the sampling frame

● Select a probability sample of 

telephone numbers within each area

● Complete the telephone interviewing 

operations with minimal 

nonresponse bias and response error

● Ensure that the desired sample 

size of children with completed 

household interviews is achieved in 

each area

To accomplish these goals, NIS–

Child uses the list-assisted method 

of landline RDD sampling (30). This 

method selects a sample of landline 

telephone numbers from banks of 100 

consecutive telephone numbers (e.g., 

617–495–0000 to 617–495–0099) that 

contain one or more directory-listed 

residential telephone numbers (known 

as the 1+ working banks). The sampling 

frame of landline telephone numbers 

is updated each quarter to include new 

banks and exclude old banks that no 

longer contain any listed numbers. 

An independent systematic sample of 

telephone numbers of the target size is 

selected each quarter in each estimation 

area, with no deeper stratification within 

each area. This method of sampling 

telephone numbers continues the method 

used by NIS–Child prior to 2005 (22).

Shifting from 78 to 56 estimation 

areas 

From 1994 through 2004, NIS–Child 

was designed to produce precise and 

direct estimates of vaccination coverage 

rates within each of 78 subnational 

estimation areas, called immunization 

action plan (IAP) areas. These IAPs were 

defined based on measles outbreaks in 

the late 1980s and early 1990s. For 2005 

and 2006 NIS–Child data collection, 

selected IAPs were rotated off the survey 

to allow vaccination coverage assessment 

in other areas that would benefit from 

vaccination coverage measurement. CDC 

decided the rotations in collaboration 

with the National Association of City 

and County Health Officers. Beginning 

in 2007, NIS–Child data collection was 

limited to the current 56 core estimation 

areas, in part to allow funding of NIS–

Teen with the 56-core-area sampling 

design. Figure 2 and Table 4 present 

the 56 core estimation areas and the 

population counts of age-eligible children 

by household telephone status as of July 

2013. 

Optional estimation areas

Beginning in 2007, a varying number 

of additional subnational or territorial 

estimation areas were added to NIS–

Child design annually to allow 

calculation of precise and direct estimates 

of vaccination coverage rates. The 

subnational and territorial areas included 

in NIS–Child for each data-collection 

year are available through CDC’s 

ChildVaxView at: https://www.cdc.gov/

vaccines/imz-managers/coverage/

childvaxview/data-reports/index.html. 

The new areas arise when individual 

states agree to sponsor extra sample for 

the designated area. In 2013, one optional 

estimation area was added: El Paso 

County, Tex.

When a new estimation area is 

added to the NIS–Child design, the 

sample in the state containing the area is 

stratified such that the new area receives 

a full estimation-area sample size (180 

effective ADP children), and the new 

rest-of-state area is allocated the number 

of effective ADP children that it received 

(in expectation) before the new area was 
Page 6  Series 1, No. 61

0 20 40 60 80 100

Cell-phone-only households Dual-user households Landline-only households Phoneless households

Idaho

New Mexico

Arkansas

Mississippi

Texas (El Paso County)

Wyoming

Oklahoma

Montana

Kentucky

Texas (City of Houston)

Texas (rest of state)1

Kansas

South Carolina

Oregon

Arizona

Texas (Bexar County)

Louisiana

Tennessee

Missouri

Michigan

Alabama

Colorado

Ohio

North Dakota

Nebraska

Georgia

Wisconsin

North Carolina

Florida

Maine

Utah

Illinois (City of Chicago)

South Dakota

Iowa

Illinois (excluding Chicago)

West Virginia

Pennslyvania (Philadelphia County only)

Indiana

Nevada

Washington

Minnesota

California

Alaska

Virginia

New Hampshire

Hawaii

Rhode Island

Pennslyvania (excluding Philadelphia County)

Maryland

District of Columbia

New York (City of New York)

Delaware

New York (excluding New York City)

Massachusetts

Connecticut

Vermont

New Jersey

1

Excludes El Paso and Bexar counties and City of Houston.

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Child, 2013.

 

Figure 2. Percentage of children aged 19–35 months in the population, by telephone status within estimation area, 2013
Series 1, No. 61  Page 7 

added. Unless the rest-of-state area is also 

sponsored by the state, no provision is 

made for precise and direct estimation for 

the new rest-of-state area. 

To illustrate, consider El Paso 

County, Tex., which is contained 

entirely within the original rest-of-Texas 

estimation area (one of the 56 core 

estimation areas). Houston and Bexar 

County are the other two core estimation 

areas in Texas. American Community 

Survey (ACS) estimates show that 

approximately 15% of age-eligible 

children in the original rest of Texas 

reside in El Paso County, and 85% reside 

in the remaining counties in the original 

rest of Texas. In years in which El Paso 

County was not sampled, the full sample 

in the original rest-of-Texas estimation 

area of 180 effective ADP children was 

distributed at random across the counties 

contained within the area, with about 

27 expected in El Paso County and 

about 153 expected in the balance of the 

estimation area. Otherwise, in years when 

El Paso County was sampled, the sample 

in El Paso County was increased to the 

full size of 180 effective APD children, 

while the remainder of original rest of 

Texas was assigned its usual allocation of 

153 effective ADP children.

Preprocessing the landline RDD 

sample

Because more than one-half of 

selected landline telephone numbers are 

business numbers or not in service, NIS–

Child has used several preprocessing 

steps to prepare the sample before dialing 

to improve the efficiency of dialing. 

These steps include:

1. An automated screening procedure 

to determine the working status of 

unlisted phone numbers; nonworking 

numbers and business numbers 

are coded as ineligible for the NIS 

surveys 

2. Matching of the remaining telephone 

numbers to lists of residential 

addresses

3. Mailing of advance notification 

letters to matched residential 

addresses

Dual-frame sampling design

Beginning in 2008, a series of 

experiments was conducted involving the 

sampling and interviewing of cell-phone 

respondents. From 2008 through 2010, 

these experiments were undertaken as 

research projects that were not tied to the 

actual NIS–Child sample in production.

In Q4/2010, a small national cellphone sample was added to the actual 

NIS–Child sample in production at 

that time to evaluate differences in 

vaccination rates between children in 

landline households and those in cellphone households, and to gain additional 

experience with interviewing persons on 

cell phones. The interviewers screened 

respondents for CPO or cell-phonemainly (CPM) status. While the existing 

landline RDD sample targeted 180 

effective APD children in each estimation 

area, the Q4/2010 cell-phone sample 

targeted 630 effective APD children 

nationally in CPO or CPM households. 

Beginning in Q1/2011, a 

somewhat larger cell-phone sample 

was implemented as part of the actual 

NIS–Child sample in production, with 

stratification by estimation area to permit 

calculation of dual-frame estimates of 

vaccination coverage in each of the 

core and optional estimation areas. In 

Q2/2011, interviewing was changed to 

a “take-all” protocol in which all cellphone respondents were interviewed 

regardless of telephone status. 

There are a few substantial 

differences between the procedures 

applied to the landline and cell-phone 

RDD samples. Because there are no 

reliable commercially available listings 

of cell-phone subscribers, the cell-phone 

sample does not use the list-assisted 

method of RDD sampling, but rather uses 

pure RDD sampling from all cell-phone 

banks in service.

The cell-phone sample is not 

prescreened to remove business and 

nonworking numbers prior to being 

released to the phone centers for 

interviewing. Because there are no 

directory listings of cell-phone numbers, 

addresses for the cell-phone sample 

cannot be obtained, and so advance 

letters are not mailed. Assignment 

of a cell-phone number to a specific 

geographic area is generally less precise 

than the assignment of a landline 

number. Consequently, for the cell-phone 

sample, the actual areas of residence as 

determined in the NIS–Child interview 

are used to adjust the size of the areaspecific sample release in subsequent 

periods.

Due to restrictions imposed by the 

Telephone Consumer Protection Act 

of 1991, in effect during the period of 

data collection covered in this report 

(2005–2014), cell-phone numbers could 

not be dialed using automated dialing 

equipment. As a result, no automated 

screening procedures were used prior to 

releasing the sample to interviewers.

Redefinition of age eligibility

Prior to Q2/2011, children’s 

eligibility for NIS–Child was calculated 

in reference to their age in months on 

the day of the screening interview. 

Theoretical and empirical analysis 

revealed that the eligibility rate could 

be increased and the sample size of 

telephone numbers decreased, while 

maintaining the survey’s precision 

requirement, by changing the definition 

of eligibility to treat children as eligible 

if they will be aged 19–35 months on 

any date during the quarter. The benefits 

to NIS–Child in cost savings due to 

the smaller released sample size of 

telephone numbers were estimated to 

be considerable, and as a result, it was 

decided to shift to the any-day-duringthe-quarter eligibility rule beginning in 

Q2/2011.

Changes for the 2012–2014 

samples

Beginning in 2012, NIS–Child 

shifted to a much larger cell-phone RDD 

sample while minimizing the cost of 

data-collection operations. Within each 

estimation area, the overall NIS–Child 

sample was allocated optimally to the 

landline and cell-phone sampling frames 

to achieve the specified constraint on the 

CV of the estimated vaccination coverage 

rate of 7.5%. 

Details of the optimum allocation 

with screening and take-all protocols are 

described elsewhere by Wolter et al. (31).
Page 8  Series 1, No. 61

Because NIS–Child continued use of 

the take-all protocol throughout 2013, 

its corresponding optimum allocation 

was used as the basis for the NIS–Child 

sample. In 2014, use of an optimal 

allocation between sampling frames was 

not possible due to budget constraints, 

resulting in a smaller allocation to the 

cell-phone sample in 2014 compared with 

2013. 

To illustrate the dual-frame sampling 

design, Table 5 lists the 57 (= 56 + 1) 

estimation areas used in 2013, excluding 

the U.S. territory samples, and shows 

the 2013 landline RDD sample size of 

telephone numbers, households, and 

children aged 19–35 months in each 

area. The released sample included 

3,395,198 landlines, 4,741 completed 

household interviews, 4,963 children 

aged 19–35 months with completed 

household interviews, and 3,152 

children with APD. Table 6 shows the 

2013 cell-phone RDD sample, which 

included 4,537,972 selected and released 

cell-phone numbers, 16,818 completed 

parental interviews, 17,499 children 

with completed parental interviews, and 

10,459 children with APD.

2013 Household-survey 

Phase 

This section addresses calling rules 

used for NIS–Child. The calling rules 

were largely unchanged from year to 

year, so this section focuses on the rules 

in use in 2013. The 2013 household 

survey phase of NIS–Child used the 

following primary calling rules for 

discontinuing call attempts to sample 

landline telephone numbers: 

● A maximum of 10 call attempts to 

ring-no-answer numbers 

● A maximum of 15 call attempts to 

numbers that resulted in a residential 

or potentially residential answeringmachine message 

● A maximum of 25 call attempts to 

likely and known households 

● No additional call attempts to hostile 

refusals 

● No additional call attempts after 

requests to “take me off your list” 

● A verbal refusal at any point after 

indicating that the household 

contained children under age 4 years 

qualified the household to receive 

a token of appreciation ($11) for 

continuing the interview

● No further attempts after a second 

verbal refusal

● No further call attempts after a hang 

up during the introduction on three 

call attempts

For cell phones, the calling rules 

were:

● A maximum of 4 call attempts to 

ring-no-answer numbers 

● A maximum of 6 call attempts to 

numbers that resulted in a personal 

(i.e., nonbusiness) or potentially 

personal voicemail message 

● A maximum of 12 call attempts to 

likely and known personal numbers 

● No additional call attempts to hostile 

refusals 

● No additional call attempts after 

requests to “take me off your list” 

● A verbal refusal by adult respondents 

at any point after indicating that they 

were the parent of a resident child 

under age 4 years, qualifying them to 

receive a token of appreciation ($11) 

for continuing the interview

● No further attempts after a second 

verbal refusal 

● No further call attempts after a hang 

up during the introduction on 3 call 

attempts 

The computer-assisted telephone 

interview (CATI) questionnaire used in 

the household survey phase of NIS–Child 

includes both a screening section to 

identify households with children aged 

19–35 months and a main interview 

section. The CATI questionnaire has been 

translated into Spanish, and Language 

Line Services (formerly part of AT&T) 

provided real-time translation of the 

interview into many other languages. 

People who are deaf, hard of hearing, or 

speech-impaired are included in NIS–

Child interviews by using text telephone 

(TTY). When a number is dialed and the 

TTY tone is encountered, the number 

is put in a separate queue for handling 

by a specialist with access to the TTY 

equipment needed to communicate with 

the household. 

2013 Household 

Questionnaire

Table 7 summarizes the content 

of each section of the 2013 NIS–Child 

household interview questionnaire. 

Links to NIS questionnaires, data, and 

documentation are available from: 

https://www.cdc.gov/vaccines/imzmanagers/nis/data-tables.html. In Section 

S, the interviewer explains the reason 

for the telephone call, including an 

introduction to the sponsoring agency 

and the purpose of the survey to the 

respondent, and screens the household 

to determine whether it contains one or 

more children aged 19–35 months. 

In Section MR, if the household has 

an age-eligible child, the interviewer 

asks the respondent whether he or 

she is the most knowledgeable person 

about the child’s vaccination history. 

If the respondent indicates that another 

person in the household is the most 

knowledgeable and that person is 

unavailable, a call back is scheduled 

to interview the most knowledgeable 

person. If a new person comes to the 

phone, parts of Section S are reread to the 

respondent. 

Prior to 2012, the NIS–Child 

questionnaire contained Sections A 

and B. When information from the 

child’s vaccination record (shot card) 

was available during the interview, the 

respondent was asked to provide that 

information in Section A. When shot 

card information was not available, the 

respondent was asked to recall from 

memory information about the child’s 

vaccination history in Section B. In 2011, 

the NIS–Child Questionnaire Redesign 

Experiment was administered to 

determine if portions of the questionnaire 

could be removed or shortened. 

Shortening the questionnaire reduced the 

burden on the respondent, consequently 

increasing interview completion rates 

and reducing the costs associated with 

each completed interview by reducing the 

time interviewers spent on the phone with 

respondents. Beginning in 2012, Section 

A was removed from the instrument, 

and Section B was modified to include a 

shorter set of questions about influenza 

vaccination and history of chicken 

pox. Section A was retained only in the 
Series 1, No. 61  Page 9 

instrument administered to the sample 

in the U.S. territory of Guam, to allow 

for a comparison of vaccination histories 

reported by households and providers, as 

little was known about the completeness 

of provider reports in this area.

Section C obtains information 

that includes the relationship of the 

respondent to the child, Hispanic 

ethnicity of the child, the race of the 

child, Hispanic ethnicity of the mother, 

the race of the mother, household income, 

educational attainment of the mother, and 

other information on the socioeconomic 

characteristics of the household and its 

eligible children. 

In Section D, the interviewer 

requests consent d to contact the child’s 

vaccination provider(s). If verbal consent 

is obtained, identifying information 

(name, address, and telephone number) 

about the vaccination provider(s) is 

requested. 

In Section E, the Health Insurance 

Module (HIM) collects data about 

the child's current insurance coverage 

and some information about periods 

without coverage that occurred since the 

child's birth. It asks whether the cost of 

vaccinations ever caused respondents not 

to get or to delay getting a vaccination 

for their child. The objective of HIM 

is to produce reasonably precise statelevel estimates of age-eligible children 

who are entitled to vaccines purchased 

by CDC’s Vaccines for Children (VFC) 

Program (see https://www.cdc.gov/

vaccines/programs/vfc/index.html for a 

more comprehensive description of the 

program). 

2013 Provider Record 

Check Phase

 When an interviewer obtains 

oral consent from a child’s parent 

or guardian to contact the child’s 

vaccination provider(s), each nominated 

provider is mailed an immunization 

history questionnaire (IHQ) (available 

from: https://www.cdc.gov/vaccines/

imz-managers/nis/data-tables.html) 

and documentation of the household’s 

consent. 

The IHQ is brief to minimize 

burden on the providers and encourage 

participation in the survey. The first page 

includes space for a label that contains 

identifying information about the child 

(including child’s name, date of birth, 

sex, and survey identification number) 

and about the provider (including 

provider name and survey identification 

number). It also contains questions about 

whether the facility has immunization 

records for the child; the dates for the 

child’s first and most recent visits to the 

practice; and questions about the facility 

to which the IHQ was mailed. The 2013 

facility questions include whether the 

facility:

● Is a federally qualified health center 

(FQHC), a rural health clinic (RHC), 

or a “look alike” FQHC or RHC

● Has been deputized to administer 

VFC Program vaccines

● Is a private practice (solo, group, or 

health maintenance organization), 

a hospital-based clinic, a public 

health department-operated clinic, 

a community health center, a rural 

health clinic, a migrant health center, 

an Indian Health Service-operated 

center, Tribal health or urban Indian 

health care facility, a military health 

care facility, a clinic associated with 

the WIC program, or a pharmacy

● Orders vaccines from the state or 

local health department

● Reported any of the child’s 

immunizations to a community or 

state immunization registry

The IHQ also collects contact 

information for the person returning the 

questionnaire.

The second page of the IHQ provides 

instructions for returning it and for 

completing a shot grid, which appears on 

the third page. This grid allows providers 

to enter the dates and types of doses of 

the vaccines administered, and to indicate 

whether they were administered at the 

provider practice that is completing the 

IHQ or at another location. 

The fourth page provides additional 

information about NCIRD, vaccine 

recommendations, and data sources and 

statistics from previous years of NIS. 

This page also provides a telephone 

number for questions or comments and 

an e-mail address along with a warning 

against sending confidential information 

about the child via e-mail. Additionally, 

this page includes definitions of terms 

used in the IHQ (e.g., federally qualified 

health center (FQHC), rural health clinic, 

FQHC look-alike, and deputization). 

 Major changes to the IHQ 

Between 2005 and 2014, the IHQ 

shot grid was modified multiple times to 

ensure the information collected about 

recommended vaccines and available 

vaccine types was accurate. In particular, 

check boxes were added to indicate the 

brands of Hib and rotavirus vaccines that 

were administered. Boxes were added 

for recording dates of receipt of the 2009 

H1N1 influenza vaccine. Space was also 

added on the shot grid to indicate the type 

of PCV vaccine, that is, PCV7 or PCV13. 

In 2012, a checkbox was added to track 

whether the child has a history of chicken 

pox. In the third quarter of 2013, several 

footnotes were added to vaccinations to 

make it easier for the person completing 

the form to code brand names: Pediarix 

was added to the DTaP-HepB-IPV 

vaccination, Pentacel was added to the 

DTaP-IPV-Hib vaccination, and the 

Hiberix booster GSK was added to the 

PRP-T vaccination. An additional vaccine 

dose checkbox, HibMenCY, was added to 

the Hib section.

PRC methodology

The PRC data-collection process 

aims to maximize responses using 

two separate methodologies: standard 

and accelerated (used near the end of 

PRC data collection to ensure cases 

were worked adequately in order to 

be included in the delivery). In the 

standard methodology, each provider 

may receive up to three separate 

mailings and a telephone call. The initial 

mailing includes a cover letter from 

NCIRD’s director describing the study 

and its goals; a copy of a Morbidity 

and Mortality Weekly Report (MMWR) 

article with national estimates from 

NIS–Child; a signed consent form; an 

IHQ for each child; a roster of all IHQs 

issued; frequently asked questions about 

the Health Insurance Portability and 

Accountability Act of 1996 (HIPAA) 
Page 10  Series 1, No. 61

and NIS; a copy of the Institutional 

Review Board (IRB) approval; a NIS–

Child Documentation Notice for HIPAA 

Accounting, which is to be placed in the 

child’s medical record; and a business 

reply envelope. 

Letters are sent to providers 2 weeks 

after the initial mailing, regardless of 

whether they have responded. The letters 

thank those who have responded and 

remind those who have not to do so. 

Five weeks after the initial mailing, a 

second mailing is sent to nonresponding 

providers. The new mailing includes 

a cover letter asking the provider to 

complete the immunization information 

for the child listed on the questionnaire, 

an IHQ, documentation of telephone 

consent, a notice for HIPAA accounting, 

an MMWR, frequently asked questions, 

an IRB approval letter, and a business 

reply envelope. Seven weeks after 

the original mailing, the remaining 

nonrespondents are contacted by 

telephone. Generally, these prompting 

calls are made to remind providers to 

return the completed questionnaires and 

to offer to mail or fax new materials 

to those providers who request them. 

In some cases, the questionnaire is 

completed by telephone. This approach 

prompts providers as inexpensively and 

as easily as possible at each stage. The 

most expensive and labor-intensive steps 

are reserved for the least-responsive 

providers. 

In the accelerated methodology, 

the initial mailing is identical to that 

used in the standard approach. Two 

weeks later, rather than send a reminder 

letter, prompting calls begin. As with 

standard prompting, the calls serve as 

a reminder to return the questionnaire; 

an opportunity to answer any questions 

the provider may have; and a time to 

encourage completion of the materials 

by phone, fax, or mail depending on 

which mode is least burdensome for 

the provider. A second mailing of the 

full set of materials is sent only upon 

provider request. This approach is aimed 

at generating an earlier return of IHQs. 

There is additional cost associated with 

prompting a larger number of providers, 

however, that cost is offset by decreases 

in the cost for reproduction, postage, and 

labor due to the removal of the reminder 

letter, mailing, and re-mails of the entire 

packet. While there are increases in the 

number of cases that enter prompting 

in the accelerated method, the net result 

is a cost savings to the project with no 

decrease in the volume or quality of the 

data collected. As a result, accelerated 

prompting was instituted as a standard 

operating procedure for PRC in 2010. 

In 2013, a web link to the MMWR 

article was added to the initial letter as a 

cost-saving measure. Separate MMWR 

documents are no longer included in the 

provider mailing packets. 

Because the goal of the PRC is to 

maximize the quantity and quality of 

immunization data returned, all providers 

are encouraged to respond in whatever 

way is least burdensome. They can 

complete the IHQ by phone, mail, or 

fax. In addition, they can fill out the IHQ 

by hand or send the child’s vaccination 

record or a record from a registry, which 

is subsequently transcribed onto an IHQ 

by trained staff.

In the last several years, providers 

have increasingly returned vaccination 

records instead of completing and 

returning the IHQ. With this trend, 

there has been a related decrease in 

the completion of the first page of the 

IHQ by providers. The majority of the 

questions on this page capture provider 

characteristics that are necessary for 

analysis of vaccinations by type of 

practice. 

In 2007, as part of the editing 

process, a donor information system 

(DIS) was instituted to minimize the 

instances of recontacting providers when 

provider-level data are missing from 

the first page. For those questions, it is 

possible to use previously completed 

IHQs to fill in the missing information. 

The DIS contains data from providers 

who completed IHQs within the previous 

2 quarters. If a new IHQ or vaccination 

record is returned with missing provider 

information, the DIS is checked to 

determine if this provider has returned an 

IHQ with completed page 1 information 

within the previous 2 quarters. If so, the 

information from those earlier returns is 

“donated” to the current IHQ as a method 

to complete the page 1 information. This 

procedure reduces the amount of time 

spent contacting providers for additional 

information and provides cost savings as 

well.

The PRC phase faces several 

important challenges. If the household 

respondent refuses to give consent to 

contact the child’s providers (consent 

is denied for about 23% of the children 

for landline respondents and 30% for 

cell-phone respondents), the approved 

interviewing protocol allows only one 

attempt at refusal conversion. Even with 

consent, some respondents are unable to 

provide sufficient contact information 

to mail to the child’s immunization 

provider(s). An extensive provider 

look-up file accessed by the telephone 

interviewer during the household 

interview helps minimize the amount 

of missing contact information. In other 

instances, providers report that they 

have no records for the child. Finally, 

some providers refuse to participate by 

either not returning completed IHQs or 

indicating that they would not like to 

receive IHQs. Data-collection efforts aim 

to minimize data loss at each of these 

points. 

Despite efforts to obtain complete 

IHQ information, each year roughly 9% 

of the children for whom the household 

interview is complete have consent, 

and yet fail to achieve APD status due 

to these various data losses. Overall, 

including cases that do not give consent 

to contact providers and failure to achieve 

APD status conditional on consent, 

about 68% of children with a completed 

household interview reach APD status for 

landline respondents and 62% for cellphone respondents.

Response Rates and Key 

Monitoring Statistics, 

2005–2014 

Cooperation rates for various stages 

of the overall interview process and 

the response rate are among the key 

indicators of survey quality. This section 

describes the key indicators and statistics 

that are monitored regularly at both the 

national and estimation-area levels. 
Series 1, No. 61  Page 11 

Tables of response rates and key 

monitoring statistics 

Table 8 presents key monitoring 

indicators at the national level for 

NIS–Child data collection from 2005 

through 2014, based on landline RDD 

samples in the 50 states and the District 

of Columbia, excluding U.S. territory 

samples. The key monitoring statistics for 

the prior NIS–Child data-collection years 

(1995–2004) are available in the NIS–

Child data user’s guides; see 

https://www.cdc.gov/nchs/nis/data_

files_09_prior.htm. 

The size and growth of NIS–Child 

are illustrated in Table 8. In 2013, 

3,395,198 landline telephone numbers 

were selected randomly by the methods 

described earlier in this report to meet 

the objective of obtaining estimates of 

vaccination coverage with the specified 

precision within each estimation area. 

Among the 363,646 households identified 

in 2013, 330,986 (91.0 %) were screened 

for the presence of children aged 19–35 

months. Of these, 325,162 (98.2%) 

did not contain an age-eligible child, 

and 5,824 (1.8%) did contain one or 

more age-eligible children. Among the 

households containing one or more 

age-eligible children, 4,792 (82.3%) 

household interviews were completed 

by adults most knowledgeable about the 

children’s vaccinations. 

One common approach for 

measuring the response rate in an RDD 

survey is the CASRO response rate, 

which has been defined by the Council of 

American Survey Research Organizations 

(32). The response rate is defined as 

the number of completed interviews 

divided by the number of eligible 

units in the sample. Given the CASRO 

approach, the unknown WRN rate in the 

set of unresolved telephone numbers is 

assumed to be the same as the observed 

WRN rate in the set of resolved telephone 

numbers, and the unknown age-eligibility 

rate in the set of screener incompletes 

is assumed to be the same as the known 

age-eligibility rate in the set of screener 

completes. 

For the 2013 NIS–Child, the CASRO 

response rate was 62.3% for the landline 

RDD sample. It can be calculated as the 

product of the resolution rate (83.2%), the 

age-screening completion rate (91.0%), 

and the interview completion rate among 

age-eligible households (82.3%). 

Table 8 lists key national monitoring 

indicators for the PRC phase of the 

NIS–Child landline RDD sample. The 

rate of obtaining consent from household 

respondents to contact their children’s 

vaccination providers was 69.6% of 

children in the 2013 sample. The number 

of IHQs that were mailed to vaccination 

providers was 4,240. This number 

exceeds the number of children with 

consent (3,453) because some children 

had more than one vaccination provider. 

Among the children with completed 

NIS–Child household interviews, 

3,152 children (63.5%) had adequate 

vaccination histories returned by their 

vaccination provider(s) to determine their 

UTD statuses.

Table 9 presents key national 

monitoring indicators for the 2013 

cell-phone RDD sample. The CASRO 

response rate was 30.5%, which can be 

written as the product of the resolution 

rate (53.8%), the screener completion rate 

(79.3%), and the interview completion 

rate (71.6%). The consent rate to contact 

the children’s providers was 67.1%, 

and among the children with completed 

NIS–Child household interviews, 10,459 

(59.8%) had adequate vaccination 

histories returned by their vaccination 

provider(s). 

Table 10 presents the response rates 

for the combined landline and cellphone RDD samples. By definition, the 

response rate is the number of households 

with a completed household interview 

divided by the estimated number of 

eligible households in the sample. Within 

each sample type, the number of eligible 

households was estimated using the 

above-mentioned CASRO assumptions. 

Given these assumptions, within each 

sample type, the CASRO response rate 

is equal to the product of the resolution 

rate, the screener completion rate, and 

the interview completion rate. For 

the combined samples, the CASRO 

response rate is defined as the total 

number of households with a completed 

interview across both samples divided 

by the estimated total number of eligible 

households across both samples (using 

CASRO assumptions within each 

sample). The combined response rate is 

also algebraically equal to a weighted 

average of the frame-specific response 

rates, where the weight given the 

response rate in the landline frame is the 

estimated number of eligible cases in the 

landline sample as a proportion of the 

estimated total number of eligible cases 

in both samples. And the weight given 

the response rate in the cell-phone frame 

is the estimated number of eligible cases 

in the cell-phone sample as a proportion 

of the total number of estimated eligible 

cases in both samples. 

As shown in Table 10, the combined 

response rates in the 2012–2014 period 

are tilted toward the response rates 

in the cell-phone sample, because the 

cell-phone sample is quite large relative 

to the size of the landline sample. This 

larger cell-phone sample is due to the fact 

that the eligible population has shifted 

substantially toward CPO telephone 

status. The downward movement in the 

combined response rate in the 2011–2013 

period, followed by a rebound in 2014, 

is due to the changing mix of landline 

and cell-phone samples across those 

years. (As noted in Table 3, an optimal 

allocation between sampling frames 

was not possible in 2014 due to budget 

constraints, resulting in a smaller 

allocation to the cell-phone sample than 

in 2013.) 

Note that the response rate does 

not account for undercoverage of the 

sampling frame and can be sensitive to 

the assumed number of eligible units 

among the nonrespondents. Alternative 

measures of potential bias that take 

into account both nonresponse and 

noncoverage are also used to monitor 

NIS–Child (see “Evaluation of NIS 

Estimates and Methods”). 

Trends in response rates and key 

monitoring statistics 

Trends in the CASRO response rate

Figure 3 displays the key indicators 

of response for the landline RDD sample 

over the 7-year period from 2005 through 

2014, excluding the U.S. territory 

samples. (For trends in NIS–Child 

response rates during the period 1995–

2004, see reference 33.)
Page 12  Series 1, No. 61

The CASRO response rate declined 

slightly from 65.1% in 2005 to 62.6% in 

2014. To understand the decline in the 

CASRO response rate, it is necessary to 

examine trends in the three component 

rates that make up the CASRO response 

rate: the resolution rate, the age-screener 

completion rate, and the interview 

completion rate. 

The resolution rate has been very 

stable, remaining at around 83.0% over 

the 7-year period. The age-screener 

completion rate has ranged from a high of 

92.8% in 2005 to a low of 90.2% in 2007. 

A high screener completion rate reflects 

the ability of the interviewers to complete 

the age-eligibility screening questions 

with resolved households. The interview 

completion rate has ranged from a high 

of 86.8% in 2007 to a low of 81.7% 

in 2011. The changes in the interview 

completion rate from year to year are 

due in part to the periodic introduction of 

topical modules to NIS–Child, and to the 

corresponding time estimate quoted to the 

respondent at the start of the interview. 

These modules increase the length of the 

survey interview, and interviewers must 

consequently give potential respondents 

an estimate of the greater length. 

With the introduction of the shortened 

questionnaire in 2012, the interview 

completion rate increased. 

Figure 4 displays the same key 

indicators of response for the cell-phone 

RDD samples from 2011 through 2014, 

excluding the U.S. territory samples.

Trends in the number of advance 

letters mailed

NIS–Child mails advance letters 

to the landline RDD sample telephone 

numbers for which it can obtain valid 

mailing addresses using a reverse-match 

procedure. The use of an advance letter 

has been shown to increase the overall 

participation and response rate in 

NIS–Child (34,35). From 2005 through 

2007, about 57% of landline telephone 

numbers released to the telephone 

centers were mailed an advance letter; 

this rate declined beginning in 2008 to 

42.9% in 2011 and to 40.8% in 2014. 

The decline is due to the declining WRN 

rate in the landline RDD sample, as 

households dropped landline telephones 

and increasingly have access only to cell 

phones (22).

Trends in the WRN rate

Among the telephone numbers in 

the landline RDD sample that have been 

resolved as nonworking, nonresidential, 

or residential, the proportion that are 

WRNs has declined steadily from 29.2% 

in 2005 to 10.8% in 2014. As fewer 

landline telephone numbers are directorylisted, and as more households become 

CPO, the WRN rate on the landline RDD 

sampling frame has declined. 

Trends in the age-eligibility rate

Among the screened households in 

the landline sample, the proportion that 

report the presence of an age-eligible 

child has declined steadily, from 3.2% 

in 2005 to 1.5% in 2014. The decline 

may be due to increasingly low survey 

participation rates for age-eligible 

households relative to age-ineligible 

households or to an increased tendency 

for age-eligible households to report zero 

children in the household in order to 

avoid survey participation. The decline 

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Child, 2005–2014.

 

Figure 3. Trends in key indicators from household and provider data collections for National Immunization Survey–Child: Landline 

random-digit-dialing sample excluding U.S. territories, 2005–2014
Series 1, No. 61  Page 13 

may also be due in part to age-eligible 

households becoming CPO at a faster 

rate than age-ineligible households. The 

households retaining landline telephones 

would then be less likely to contain 

an age-eligible child, leading to lower 

observed age-eligibility rates in the 

landline RDD sample.

Trends in the provider consent rate

Of the children with complete 

household interviews, the proportion for 

whom consent to contact vaccination 

providers was obtained varied over the 

2005–2014 period, ranging from a high 

of 81.0% in 2006 to a low of 69.6% 

in 2013 for landline respondents. For 

cell-phone respondents, the proportion 

for whom consent to contact vaccination 

providers was obtained also varied over 

the 2011–2014 period, ranging from 

75.0% in 2011 to 66.9% in 2014.

Trends in the percentage of children 

with APD

In the landline RDD sample, 

the proportion of children with APD 

(Table 8) varied between 63.3% and 

72.3% during the 2005–2014 period. 

The increase from 2005 through 2006 

was mainly due to a higher IHQ (or 

vaccination record) return rate, which 

increased from 88.0% in 2005 to 94.5% 

in 2006; the return rate has remained well 

over 91.0% since 2006. (The lower rate 

in 2005 was due to a delay in funding 

that resulted in a suspension of PRC data 

collection for Q1/2005 for a period of 6 

months.) During 2011–2014, in the cellphone RDD sample, the proportion of 

children with APD (Table 9) ranged from 

58.9% to 66.7%. The variability was due 

to variation in the proportion of such 

respondents for whom consent to contact 

vaccination providers was obtained.

Although the CASRO response rate 

in the landline sample declined slightly 

from 2005 through 2014, the product 

of the CASRO response rate and the 

percentage of children with APD (a 

measure of the overall success of NIS–

Child in obtaining vaccination data for 

age-eligible children) was higher in 2012 

(43.8%) than it was in 2005 (41.4%) and 

has remained relatively stable in 2013 

and 2014 (39.6%). The CASRO response 

rate in the cell-phone sample rose from 

25.2% in 2011 to 33.5% in 2014, while 

the product of the CASRO response rate 

and the APD rate has ranged from 16.8% 

in 2011 to 19.7% in 2014.

Potential limitations of APD: 

Incomplete ascertainment of providerreported vaccination histories

Several steps are taken to maximize 

the number of children whose providerreported vaccination data are sufficient 

to determine their vaccination status. 

Even for such children, however, the 

vaccination history reported in the PRC 

may not be complete. As a result, NIS–

Child estimates of vaccination coverage 

for children with APD are likely to be 

lower than the true level of coverage for 

these children. 

Children with APD include those 

for whom all identified vaccination 

providers returned the IHQ or medical 

records containing a vaccination 

history. In addition, if some but not 

all identified providers responded and 

reported vaccination histories, a set of 

rules determines whether the child is 

0

20

40

60

80

100

Interview completion rate

Screening completion rate

Children with adequate provider data

Resolution rate

CASRO1 response rate

2011 2012 2013 2014

Percent 1

Council of American Survey Research Organizations.

 

Figure 4. Trends in key indicators from household and provider data collections for National Immunization Survey–Child: Cell-phone 

random-digit-dialing sample excluding U.S. territories, 2011–2014
Page 14  Series 1, No. 61

considered to have APD. From 2005 

through 2014, these rules were based on 

the following primary criteria: 

● Whether the responding provider(s) 

reported the child as UTD with the 

recommended number of doses of 

vaccines in the 4:3:1:3 series (4 or 

more doses of DTaP, 3 or more doses 

of polio, 1 or more doses of any 

MCV, and 3 or more doses of Hib 

vaccine)

● Whether the child was UTD for the 

4:3:1:3 series when vaccinations 

given after the date of the household 

interview were counted 

● Whether the responding provider(s) 

reported at least as many doses of the 

key recommended vaccines as the 

household respondent 

Children who received zero 

vaccinations are also considered to have 

APD. A child is considered to be a “zeroshot” child if either:

● The household respondent reported 

zero vaccinations for the child and 

identified zero providers

● The household respondent reported 

zero vaccinations for the child and 

identified one or more providers, all 

of the identified providers returned 

IHQs or medical records, and 

none of the providers reported any 

vaccinations for the child

In 2013, among the 4,963 children 

in the RDD landline sample for whom 

household respondents completed the 

interviews (excluding the U.S. territory 

samples), 3,152 (63.5%) children had 

APD. Among these, 25 children (0.8%) 

were classified as zero-shot children, 

2,367 (75.1%) were reported by the 

household respondent as having only 

one vaccination provider, and 785 

(24.9%) were reported as having two or 

more vaccination providers. In the latter 

group, 280 children (35.7%) did not 

have vaccination histories reported by all 

identified providers. 

In 2013, among the 17,499 children 

in the RDD cell-phone sample for whom 

household respondents completed the 

interviews (excluding the U.S. territory 

samples), 10,459 (59.8%) children 

had APD. Among these, 126 (1.2%) 

were classified as zero-shot children, 

7,303 (69.8%) were reported by the 

household respondent as having only 

one vaccination provider, and 3,156 

(30.2%) were reported as having two or 

more vaccination providers. In the latter 

group, 1,223 children (38.8%) did not 

have vaccination histories reported by all 

identified providers. 

When a child has two or more 

vaccination providers, the vaccination 

history may be scattered in such a way 

that no single provider has the entire 

vaccination history. A child’s vaccination 

history may be ascertained (determined) 

incompletely for one or more vaccines 

when not all providers respond and the 

reported information does not show that 

the child is UTD. Literature suggests that 

children with an incompletely determined 

vaccination status may be found to be 

UTD when their entire vaccination 

history from all providers is assembled 

and examined (36–39).

Figure 5 shows trends in the 

percentage of children with two or more 

providers among children with APD from 

the 2005–2014 landline RDD samples, 

excluding the U.S. territory samples. 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Child, 2005–2014.

 

Figure 5. Trends in percentages of children with two or more providers among children with adequate provider data, and children with one 

or more providers not reporting among children with adequate provider data and two or more providers, for National Immunization 

Survey—Child: Landline random-digit-dialing sample excluding U.S. territories, 2005–2014
Series 1, No. 61  Page 15 

This percentage stayed reasonably 

steady from 2005 through 2008, ranging 

between 25% and 27% before increasing 

in the 2009–2011 period. This percentage 

decreased from 2011 through 2014, 

and was at 28.1%. The increase in 2009 

and 2010 was due to a questionnaire 

change made in New York and California 

between Q3/2009 and Q2/2010; during 

these quarters, respondents in New York 

and California were asked to identify 

the hospital where the child was born, 

resulting in an increase in the number 

of providers identified per child. This 

change was made to determine if the 

NIS PRC was accurately capturing the 

number of birth doses of HepB being 

given at hospitals. Figure 5 also shows, 

among children with APD and two or 

more providers, trends in the percentage 

of children who have fewer than all 

identified providers returning IHQs or 

medical records containing a vaccination 

history. This rate was 52.0% in 2005 and 

ranged between 35.1% and 44.6% from 

2006 through 2014. The higher rate in 

2005 reflects the lower IHQ return rate 

in 2005, which was due to the delay 

in funding for PRC data collection for 

Q1/2005.

Figure 6 shows trends in the 

percentage of children with two or more 

providers among children with APD 

from the 2011–2014 cell-phone samples, 

excluding the U.S. territory samples.

Because of the potential for 

incomplete ascertainment of some 

children’s vaccination histories, users of 

NIS–Child data who wish to compare 

vaccination coverage rates between 

subpopulations are cautioned to evaluate 

whether these differences are statistically 

significant after adjusting for differing 

rates of incomplete ascertainment 

between the subpopulations (40). 

Representation of the 

Target Population 

The NIS–Child sampling frames 

do not directly provide representation 

of children living in households without 

access to any telephone (i.e., phoneless 

households) or of children who live in 

landline households whose landline 

number is not in a bank of telephone 

numbers containing at least one listed 

number and whose parents do not use 

cell phones. Also, prior to Q4/2010, 

NIS–Child did not include direct 

coverage of children living in CPO 

households. All such children not directly 

represented through the sampling frame, 

however, were represented indirectly 

through the NIS–Child estimation 

procedure, described in “Estimation 

Methodology for NIS–Child.” According 

to the National Health Interview Survey 

(NHIS), in the second half of 2013, 2.5% 

of children under age 18 years lived in 

phoneless households, and 47.1% lived 

in CPO households (22). Model-based 

state-level estimates of the telephone 

status of households with children aged 

19–35 months show that the prevalence 

of CPO households in 2013 ranged from 

approximately 38% percent in Vermont 

to 77% in Idaho. (For a description of the 

general method of state-level estimation, 

see “Wireless Substitution: State-level 

Estimates From the National Health 

Interview Survey, January 2007–June 

2010” (41). Using the general method, 

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Child, 2011–2014. 

Figure 6. Trends in percentages of children with two or more providers among children with adequate provider data, and children with one 

or more providers not reporting among children with adequate provider data and two or more providers, for National Immunization 

Survey—Child: Cell-phone random-digit-dialing sample excluding U.S. territories, 2011–2014 
Page 16  Series 1, No. 61

NIS–Child prepares state-level estimates 

of population size for the domain 

of children aged 19–35 months by 

telephone status every year in support of 

the survey’s estimation procedure; see 

Table 4 and “Estimation Methodology 

for NIS–Child.” The augmentation of 

the NIS–Child sampling design with 

a cell-phone RDD sample starting in 

2011 extended the direct representation 

to include children living in CPO 

households. Estimates of the proportion 

of landline households not covered by the 

landline sampling frame (i.e., households 

in zero-banks) vary, with different studies 

estimating the proportion to be between 

8% and 20% (42–44). 

Estimation 

Methodology for NIS–

Child 

Introduction

The purpose of estimation in 

NIS–Child is to infer the vaccination 

coverage rates in the target population 

of children aged 19–35 months, 

based on the data collected from the 

sample. The NIS–Child estimation 

(or weighting) procedures make 

adjustments for variation in sampling 

rates, differential response rates, and 

differential undercoverage in the sample 

relative to the population to produce 

accurate estimates at different levels. 

The estimates and variance estimates 

are produced for each NIS–Child 

estimation area, for each state, and 

for the country. Through June 2014, 

estimates were produced twice each 

year, with a lag of 6 months between the 

completion of household data collection 

and the production of the estimates. 

The annual June NIS–Child delivery 

includes the Q1–Q4 surveys from the 

previous calendar year, and the annual 

December delivery includes the surveys 

from the last one-half of the previous 

year (Q3–Q4) and the first one-half of 

the current year (Q1–Q2). The annual 

December delivery of cross-year files 

was terminated following delivery of the 

Q3/2013–Q2/2014 file. The estimation 

process is preceded by a number of steps, 

such as imputation of certain missing 

items and linking the household and PRC 

data. 

In preparation for computing 

accurate estimates of vaccination 

coverage rates, NIS–Child derives survey 

weights for sampled children who have 

a completed household interview and for 

the subset of children for whom adequate 

provider data were obtained. NIS–Child 

utilizes a complex multistage weighting 

approach to account for probabilities 

of selection, adjust for various types of 

nonresponse, and calibrate weighted 

survey counts to population control totals. 

The objective of the weighting approach 

is to minimize the mean squared error 

(MSE) of the estimator of the vaccination 

coverage rate. Overall, there are two 

types of survey weights created for NIS–

Child: child-level RDD survey weights, 

used to analyze household-reported 

interview data; and child-level provider 

survey weights, used to analyze providerreported vaccination history data.

The following sections will discuss 

a) the imputation procedure used to 

complete missing values for variables 

that are used in the weighting procedure; 

b) the weighting procedure employed 

in NIS–Child throughout 2005–2010, 

during which the NIS–Child sample was 

based on a single-frame landline RDD 

survey design (estimation methodology 

used in earlier years of NIS–Child is 

described in Smith et al. [21]); c) the 

weighting procedure used from 2011 

through 2014 to address the dual-frame 

survey design (using both landline and 

cell-phone frames); and d) the estimator 

of the vaccination coverage rate and the 

application of the Taylor series method as 

an estimator of its variance. 

Imputation of Weighting 

Variables, 2005–2014

Among households that respond 

to the interview, some individual items 

(such as race of child or education of the 

mother) may go unanswered. NIS–Child 

imputes values for variables used in the 

weighting process. 

The NIS–Child structured imputation 

uses the “hot-deck” procedure to bring 

together data for children who are similar 

on selected characteristics and then to fill 

in missing items for a child (“recipient”) 

using corresponding items for a child 

that has no such missing items (“donor”). 

This is done by categorizing child records 

into imputation cells using “class” 

variables, with imputation carried out 

separately within each imputation cell. 

Within a particular imputation cell, 

all child records are sorted using auxiliary 

variables determined to be related to, or 

good predictors of, the missing variable. 

A child with a missing data value is 

given the same response as the child not 

missing that value just above it in the 

ordered sort. With the implementation 

of the dual-frame sample design, 

imputations for 2011–2014 were done 

separately by sample frame in almost all 

cases, with cross-donation allowed only 

when necessary. Records are restricted 

to being used four times at most as a 

donor for imputing a variable. Imputation 

occurs in a hierarchical fashion, because 

some variables are needed as class and 

sort variables for the imputation of other 

variables.

NIS–Child does not use imputation 

extensively. Table 11 shows the overall 

item nonresponse rate among landline 

sample cases by year, from 2005 through 

2014, for variables subject to imputation. 

Item nonresponse rates ranged from 0.0% 

to 10.2%; for most variables, the item 

nonresponse rate is generally less than 

2% and often less than 1%. The higher 

item nonresponse rate for race mainly 

reflects Hispanic respondents who did 

not report a race. Table 12 shows the 

item nonresponse rate among cell-phone 

sample cases for 2011–2014. Results 

were similar to those observed for the 

landline sample, ranging from 0.1% to 

8.0%, although cell-phone sample item 

nonresponse rates for race are somewhat 

higher than those for the landline sample.

2005–2010 Single-frame 

Estimation Methodology

The NIS–Child weighting scheme 

for estimation based on the landline 

sample, used for each year from 2005 

through 2010, involved three broad 

stages: 1) accounting for probabilities of 
Series 1, No. 61  Page 17 

selection, adjusting for various types of 

household nonresponse, and combining 

the four quarterly samples (resulting in 

annual household weights); 2) adjusting 

for nonrepresentation of nonlandline 

telephone households and failure of the 

sampling frames to represent the entire 

population of children (resulting in childlevel interview weights); and 3) adjusting 

for provider nonresponse and controlling 

survey weights to independent population 

controls (resulting in provider-phase 

weights). Each of these broad stages 

included a number of steps, as shown in 

Figure 7.

The first six steps (described above) 

of the three-stage NIS–Child weighting 

scheme produce the final household 

weights, the next three steps produce 

the final RDD-phase child weights 

used to generate estimates for variables 

collected in the NIS–Child household 

interview, and the last two steps adjust 

for provider nonresponse and produce 

the final provider-phase child weights 

used to generate vaccination coverage 

rate estimates and estimates for variables 

collected from providers in the IHQ. The 

stages and steps within each stage did 

not change across the 2005–2010 period; 

however, details for individual steps have 

been refined across time, as indicated in 

the following descriptions.

Household-level weighting

The first stage of weighting involves 

six steps, of which the first five are 

carried out separately within each 

survey quarter and sampling area. Step 

6 is carried out separately within each 

sampling area. These steps are carried out 

to derive an annual household weight. 

Step 1. Base weights—Each 

telephone number sampled by NIS–Child 

receives a base sampling weight that is 

equal to the reciprocal of the probability 

of selecting the telephone number into 

the sample. The base weight is computed 

separately within each quarter.

Steps 2–4. Adjustment for 

nonresolution of telephone numbers, 

screener nonresponse, and household 

interview nonresponse—Adjustments 

to the survey weights are necessary 

to account for telephone numbers for 

which the WRN status is not resolved 

(Step 2); telephone numbers for which 

the screening interview is incomplete 

(Step 3); and households for which the 

household interview is incomplete 

(Step 4). Because little covariate 

information is known at this point about 

the households with sampled telephone 

numbers, each adjustment is made within 

cells formed by cross-classifying the 

sample by the directory-listed status 

of the telephone number and by two 

telephone-exchange level variables: 

percentage of the population that is white 

(75% or greater, less than 75%), and 

metropolitan statistical area (MSA) status 

(in MSA, not in MSA). 

The exchange-level variables reflect 

census summary data at the census-tract 

level. The telephone vendor provides a 

crosswalk between tracts and exchanges, 

based on the addresses of listed telephone 

numbers, which is used to translate the 

census summary data to exchange-level 

data. These cell definitions are used 

for all three weight adjustments. If the 

number of cases (resolved, screened, and 

interviewed, respectively) is fewer than 

20 in a cell, the categories are collapsed 

prior to adjustment, in the reverse order 

as listed above. These adjustments 

assume that, after controlling for known 

covariates, the rate of WRNs among 

unresolved landline phone numbers is 

the same as the rate of WRNs among 

resolved landline phone numbers (Step 

2); the incidence of eligible children in 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization 

Survey–Child, 2005–2010.

 

Figure 7. Weighting flowchart for National Immunization Survey–Child, 2005–2010
Page 18  Series 1, No. 61

unscreened households is the same as that 

among screened households (Step 3); and 

noninterviews among eligible households 

are considered as missing at random 

(Step 4).

Step 5. Adjustment for multiple 

telephone lines—Among the households 

that completed the main interview, 

some reported having more than one 

residential telephone number for home 

use (excluding cell-phone numbers and 

telephone numbers used only for fax or 

computer). An adjustment to the weight 

is required for these households to 

compensate for their multiple chances of 

selection. The adjustment, which divides 

the survey weight from Step 4 by the 

reported number of landline telephone 

numbers, is calculated separately for each 

household. The number of telephone lines 

used in deriving the adjustment is capped 

at three, both to control variability in the 

adjusted survey weights and to guard 

against reporting bias.

Step 6. Combination of quarterly 

samples—The survey weights resulting 

from Step 5 relate to a given quarterly 

sample, each of which represents the 

full sampling-frame population of ageeligible children in landline telephone 

households. However, annualized 

estimates of vaccination coverage are 

produced by combining data from 4 

consecutive quarters. Consequently, the 

quarterly weights need to be adjusted 

when the 4 quarters are combined. Since 

NIS–Child completed sample sizes in 

different quarters can vary, the adjustment 

factor for a quarter is computed as the 

number of households with a complete 

interview in the quarter divided by 

the total number of households with a 

complete interview over the 4 quarters.

The survey weights resulting 

from Step 6 represent the final annual 

household weights.

Child-level weighting

The next weighting step shifts from 

the household level to the child level. 

All age-eligible children from screened 

households are selected into NIS–Child. 

The initial child-level weight for each 

age-eligible child in a household with 

a completed household interview is the 

corresponding annual household weight 

from Step 6. Three weight adjustments 

are carried out separately within each 

estimation area. 

Step 7. Adjustment for noncoverage 

of children in nonlandline telephone 

households—The NIS–Child landline 

RDD sample does not cover households 

without access to any landline 

telephones, so an adjustment is required 

to compensate for the noncoverage of 

children living in households without 

access to a landline telephone.

This adjustment is applied to weights 

for children in households reporting an 

interruption in landline telephone service 

of 1 week or more during the past 12 

months. The adjustment approach is 

based on empirical evidence suggesting 

that socioeconomic, demographic, 

and vaccination characteristics of 

phoneless households are more similar 

to households with an interruption 

in landline telephone service than to 

other landline telephone households. 

(45,46). The adjustment for children in 

households reporting a telephone service 

interruption is capped at three times the 

adjustment for children in households not 

reporting a telephone service interruption 

to control variability in the adjusted 

survey weights.

This adjustment was initially 

intended to provide a means of 

representing children in phoneless 

households. Over time, however, the 

adjustment increasingly provided a 

means of representing children in both 

phoneless and CPO households. Although 

there were concerns with use of this 

adjustment to represent the latter category 

of children, research suggested use of 

this adjustment would become even more 

appropriate as the proportion of CPO 

households increased (47).

Step 8. Simple poststratification 

to population controls—While the aim 

of Step 7 is to reduce bias due to the 

noncoverage of the nonlandline telephone 

population, NIS–Child is undoubtedly 

also subject to differential coverage of 

the population by race and ethnicity and 

other factors. As in almost any census or 

survey, some categories of persons are 

underreported at a higher rate than other 

categories. NIS–Child uses a simple 

poststratification scheme to reduce bias 

due to differential coverage.

Within each estimation area, the 

poststratification cells are defined by the 

race or ethnicity of the child’s mother 

(Hispanic, non-Hispanic black alone, 

all other), educational attainment of the 

child’s mother (less than or equal to 

12 years, more than 12 years), and age 

category of the child (19–23 months, 

24–29 months, 30–35 months). To 

control sampling variability, cells with 

fewer than 25 children are collapsed 

with neighboring cells. The derivation 

of population controls is presented 

following discussion of the weighting 

steps.

Step 9. Raking adjustment to 

population controls—During the simple 

poststratification adjustment, a number 

of cells have to be collapsed, either 

to ensure the minimum cell size of 25 

records or to avoid an adjustment factor 

greater than 2. As a result, the marginal 

totals of the poststratified weights for 

some categories of the poststratification 

variables do not exactly match the 

population control totals at the marginal 

level within an estimation area. In 

addition, one other desired demographic 

variable—sex of the child—could not be 

used in simple poststratification to avoid 

sparseness of the weighting adjustment 

cells. To gain agreement with marginal 

totals, a raking-ratio estimator (48) is 

applied to the poststratified weights by 

using the following raking dimensions 

within each estimation area: three 

categories of race or ethnicity of the 

child’s mother (Hispanic, non-Hispanic 

black alone, all other); two categories 

of educational attainment of the child’s 

mother (12 years or less, more than 12 

years); three categories of age of the child 

(19–23 months, 24–29 months, 30–35 

months); and sex of the child (male, 

female). The raking adjustment utilized 

one additional raking dimension for 2005 

and 2006, defined by telephone-service 

interruption status (interruption, no 

interruption).

The various adjustments may 

occasionally yield some extreme survey 

weights that are substantially larger 

than other survey weights in the same 

estimation area, which could adversely 

affect variances of the estimated 

vaccination coverage rates. Thus, in 

calculating the final child-level interview 
Series 1, No. 61  Page 19 

weights, checks are made for weights that 

exceed a threshold defined as the median 

weight plus six times the interquartile 

range of the weights in the estimation 

area. Any weight exceeding this threshold 

is truncated to a value slightly lower than 

the threshold value. The overall goal of 

truncation is to reduce the mean squared 

error of the estimators.

Raking and trimming are iterated 

until convergence of the weighted counts 

to the population controls is achieved. 

The survey weights resulting from Step 

9 are the child-level interview weights, 

which weight up to the overall population 

of age-eligible children, including 

children for whom provider consent 

was not obtained, provider consent was 

obtained but the provider(s) did not 

respond to the IHQ, provider consent 

was obtained but adequate provider data 

were not obtained, and provider consent 

was obtained and the provider data 

were determined to be adequate. The 

child-level interview weights are used 

to generate child-level estimates for data 

collected from the household interview. 

Provider-phase weighting

The third stage of weighting 

involves two steps. Children who had 

no vaccinations (zero-shot kids) are 

not included in these steps. These are 

children without provider-reported 

vaccination histories for whom the 

household respondent reported that 

the child has zero vaccinations. See 

Appendix II for the complete definition 

of zero-shot status.

Step 10. Adjustment for provider 

nonresponse—For children for whom 

a household interview was completed, 

the respondent was requested to provide 

information to locate the child’s 

vaccination provider(s) and consent to 

contact those provider(s). After obtaining 

the provider information and consent, 

the provider was contacted and asked 

to report vaccination information for 

the child. Provider data are missing 

for approximately 30% of the children 

for whom the household interview 

is complete, due to various factors, 

including parental nonconsent, provider 

nonresponse, and provider failure to 

supply adequate vaccination data. To 

compensate for this form of nonresponse 

(missing APD), NIS–Child segments 

the children with a completed household 

interview in each estimation area into five 

essentially equal-sized cells on the basis 

of their model-based predicted response 

propensity (i.e., response to the provider 

phase of the survey or the event of 

having APD). Then, within each of these 

cells the child-level interview weight of 

each child with adequate provider data 

is multiplied by an adjustment factor 

equal to the ratio of the total child-level 

interview weight for all children to the 

total child-level interview weight for the 

children with APD. For more details on 

this method of adjustment, see Smith et al. 

(20).

A child’s response propensity is 

the predicted probability that the child 

has APD, calculated from a logisticregression model. The model is based 

on the data from all children with 

a completed household interview, 

excluding unvaccinated children, and 

the outcome or dependent variable is an 

indicator of whether the child has APD. 

In preparation for building the model, 

a list of potential predictor variables 

was assembled. These variables, 

available from the completed household 

interviews, have been found to be 

associated with vaccination status. Those 

characteristics were also relevant to the 

presence or absence of provider data, 

because empirical results suggested that 

children who have provider data are more 

likely to be UTD on their vaccinations 

than children who do not have provider 

data.

The logistic-regression model is 

updated annually, using NIS–Child data 

from the corresponding 4-quarter period. 

As such, the set of variables selected for 

inclusion in the model may change from 

year to year. Table 13 provides the list of 

variables considered for inclusion in the 

model, along with information showing 

which variables were selected each year.

Step 11. Raking adjustment 

to population controls—While the 

propensity-based adjustment reduces 

bias due to missing provider data, 

the adjusted weights do not generally 

match the control totals used for simple 

poststratification or raking or the 

weighted totals of other variables thought 

to be associated with being UTD. It is 

possible, however, to arrive at weights 

that satisfy all these constraints through 

further raking. Within each estimation 

area, final adjusted weights are computed 

by a raking procedure using the following 

variables: race or ethnicity of the child 

(Hispanic, non-Hispanic black only, all 

other); educational attainment of the 

child’s mother (12 years or less, more 

than 12 years); age of child (19–23 

months, 24–29 months, 30–35 months); 

sex of child (male, female); firstborn 

status of child (yes, no); and child’s 

response propensity adjustment cell

(q = 1,2,3,4,5).

The survey weights resulting from 

Step 11 represent the provider-phase 

weights and are used to generate childlevel estimates for data collected in the 

PRC and to generate official estimates 

of vaccination coverage, as described in 

a later section. Provider-phase weights 

for zero-shot kids are defined to be their 

child-level interview weights.

Summary information relative to 

sample sizes and variability of child-level 

interview and provider-phase weights is 

provided in Table 14.

Population control totals

The NIS–Child survey weights are 

controlled to independently derived 

estimates of the total number of ageeligible children in each estimation 

area. Because the NIS–Child target 

population is children aged 19–35 

months, population controls are derived 

from natality data produced by the 

National Vital Statistics System (49), 

rather than from sources such as the U.S. 

Census Bureau, which typically provide 

estimates based on smaller samples and 

by single year of age or for age categories 

defined by a range of whole years of age. 

The natality data also yield population 

totals for several important subgroups 

to which it is desirable to control the 

weights, including subgroups defined by 

race or ethnicity, mother’s education, sex, 

and age of child.

For each estimation area, the natality 

files (for the time period 19–35 months 

prior to the midpoint of the 4-quarter 

period to be estimated) provide the size 

of the population of eligible live births 
Page 20  Series 1, No. 61

(e.g., for the 2007 NIS–Child, live births 

occurring between July 1, 2004, and 

November 30, 2005, inclusive. These 

children would have been aged 19–35 

months on June 30, 2007, the midpoint 

of the 2007 data year). The raw counts of 

births are adjusted to reflect three factors: 

infant mortality, immigration 

(i.e., children aged 19–35 months 

living in the United States who were 

born outside the United States), and 

domestic migration (i.e., children aged 

19–35 months living in one area who 

were born in a different area). The first 

two adjustments are applied separately 

for Hispanic children, non-Hispanic 

black children, and non-Hispanic white 

children who are also of other races. 

Population control totals for 2006–2008 

included an additional adjustment to 

account for the out-migration from 

Orleans Parish, La., and surrounding 

areas associated with Hurricane Katrina.

Infant mortality

The period linked birth/infant death 

National Vital Statistics Reports for a 

given year are referenced to obtain 1-year 

infant mortality rates for each racial or 

ethnic group within each state (50). These 

rates are applied to the counts of live 

births. However, this is an overestimate 

of the survivors to NIS–Child eligibility 

because it does not consider the deaths 

that occur between ages 12 and 19 

months. The most recent life table 

available from NCHS’ National Vital 

Statistics Reports was used to inflate 

the 1-year mortality rates to account for 

this additional time period (with three 

different adjustments for three different 

child-age subgroups). 

Immigration

For 2005–2009, Public Use 

Microdata Sample (PUMS) data from 

the 2000 decennial census were used 

to estimate the number of immigrants 

to add. In order to obtain more current 

estimates of immigration rates, beginning 

with the 2010 population estimates 

process, the most recent 3-year American 

Community Survey (ACS) PUMS data 

were used to estimate the number of 

immigrants to add for the 50 states and 

the District of Columbia. Because ACS 

is not conducted in the U.S. territories, 

the most recent decennial census 

PUMS sample is used for estimating 

immigration and migration to and from 

the U.S. territories. 

Domestic migration

The most recent 3-year ACS PUMS 

and decennial census PUMS include state 

of current residence for children aged 1 

and 2 years, and also the state where the 

child was born. This information cannot 

be used directly to estimate geographic 

mobility, because some children are born 

in a state different from their state of 

residence (e.g., children born in hospitals 

in the District of Columbia to mothers 

who live in Maryland). Vital statistics 

data on the state of residence of the 

mother at the time of birth and the state 

where the birth occurred are used to 

adjust the PUMS estimates to reflect only 

geographic mobility. 

2011–2014 Dual-frame 

Estimation Methodology 

Beginning in 2011, NIS–Child 

implemented a dual-frame sampling 

design, with the cell-phone sample design 

utilizing a “take-all” approach, in which 

all eligible cell-phone households are 

targeted for interview. For Q1/2011, the 

NIS sample design called for screening 

the cell-phone sample to restrict inclusion 

to CPO and CPM households 

(“screening” approach). NIS shifted to 

the take-all design in Q2/2011. The 

dual-frame weighting scheme involves 

the same three broad stages as for the 

landline-weighting scheme used in the 

2005–2010 period and discussed 

previously: accounting for probabilities 

of selection and adjustment for household 

nonresponse (yielding annual household 

weights), adjusting for nonrepresentation 

of phoneless households and failure of 

the sampling frames to represent the full 

population of children (yielding childlevel interview weights), and adjusting 

for provider nonresponse and controlling 

survey weights to independent population 

controls (yielding provider-phase 

weights). The objectives of the dualframe weighting approach are to account 

for overlap between the two sampling 

frames and to minimize the mean-square 

error of the estimated vaccination 

coverage rate at the estimation-area level.

Overview of dual-frame 

estimation and differences from 

landline-frame estimation 

Survey weights for the landline and 

cell-phone samples must be integrated 

to provide weights yielding appropriate 

and efficient estimates for the full target 

population of children aged 19–35 

months. The landline and cell-phone 

sampling frames overlap in coverage of 

the age-eligible population (i.e., children 

in dual-user households) and exclude 

a small portion of the age-eligible 

population (i.e., children in phoneless 

households). Consequently, the estimated 

coverage of the landline sampling frame 

for 2013 NIS–Child estimates was 52.9% 

of the child population, and it was 94.5% 

for the cell-phone sampling frame.

In addition to carrying out weighting 

steps as in the landline-frame estimation 

methodology, the dual-frame estimation 

methodology focuses on adjustment for 

overlap to minimize resultant variability 

in estimates from the dual-user domain 

and on adjustment for noncoverage 

of age-eligible children in phoneless 

households. In addition, survey weights 

must also adjust for any sample-frame 

coverage error associated with the 

landline-only (LLO) and CPO domains.

Adjustment to population controls by 

telephone status

Prior to adjusting for overlap 

between the landline and cell-phone 

samples, survey weights are adjusted to 

agree with independent estimates of the 

size of the population by telephone status, 

with adjustment to population estimates 

of the dual-user population being made 

separately for the landline sample and the 

cell-phone sample.

Telephone status population control 

totals are derived at the estimation-area 

level using a similar small area modeling 

approach as described in Blumberg et al. 

(51); see Table 4.
Series 1, No. 61  Page 21 

Adjustment for overlap of landline and 

cell-phone sampling frames

The landline-sampling frame 

covers the population in dual-user 

households as well as the population 

in LLO households, while the cellphone sampling frame also covers the 

population in dual-user households 

as well as the population in CPO 

households. Thus, the sampling design 

supports one estimator each for the LLO 

and CPO domains and two estimators for 

the dual-user domain.

The sum of the telephone statusadjusted weights for the landline sample 

(which estimates the number of ageeligible children in landline households) 

and the sum for the cell-phone sample 

(which estimates the number of 

age-eligible children in cell-phone 

households) each encompass age-eligible 

children in dual-user households. The 

landline sample also encompasses ageeligible children in LLO households, and 

the cell-phone sample also encompasses 

age-eligible children in CPO households. 

Thus, when combining the landline and 

cell-phone samples, the telephone statusadjusted weights for children in dualuser households within each estimation 

area must be composited so the sum 

of the further adjusted weights across 

landline and cell-phone samples provides 

an appropriate estimate of age-eligible 

children in dual-user households (i.e., 

does not double count the number of 

children in dual-user households), while 

also providing efficient estimates for this 

domain.

Compositing of the telephone statusadjusted weights for the landline and 

cell-phone sample cases is carried out 

using factors derived so that the resulting 

composited weights yield minimum 

variance estimates. This compositing 

takes the form

ŶDa=λa ŶL(D)a + (1 – λa) ŶC(D)a ,

where ŶL(D)a is the estimated total of a 

characteristic of interest in estimation 

area a (e.g., total number of children in 

the population who are breast fed or UTD 

for the 4:3:1:3:3:1 vaccine series), based 

on children from the landline sample 

living in dual-user households; and ŶC(D)a

is the estimated total in estimation area a

based on children from the cell-phone 

sample living in dual-user households.

The composition factors λa that 

minimize the variance of the estimated 

total for the dual-user domain (assuming 

ŶL(D)a and ŶC(D)a are unbiased) can be 

expressed as

where nL(D)a is the number of children 

in estimation area a from the landline 

sample living in dual-user households, 

nC(D)a is the number of children in 

estimation area a from the cell-phone 

sample living in dual-user households, 

DEFFL(D)a is the design effect (i.e., a 

weighting effect) associated with children 

in dual-user households from the landline 

sampling frame in estimation area a, and 

DEFFC(D)a is the design effect (i.e., a 

weighting effect) associated with children 

in dual-user households from the cellphone sampling frame in estimation area 

a.

Adjustment of the weights is then 

implemented in consideration of the 

derived compositing factors:

Wj

'

 =

Wj

 , j∈ L(LLO), a

λaWj , j ∈ L(D), a

(1 – λa)Wj

 , j ∈ C(D), a

Wj , j ∈ C(CPO), a

where Wj represents the weight for 

sample unit j following the preceding 

weighting step, L(LLO) indicates the set 

of children from the landline sample 

living in LLO households, L(D) indicates 

the set of children from the landline 

sample living in dual-user households, 

C(D) indicates the set of children from 

the cell-phone sample living in dual-user 

households, and C(CPO) indicates the set 

of children from the cell-phone sample 

living in CPO households.

Other refinements to the NIS–Child 

estimation methodology to 

accommodate the dual-frame sample 

design

Other refinements to the NIS–Child 

landline estimation methodology reflect 

the addition of the cell-phone sample. 

First, in Steps 1–6, base weights are 

derived and adjustments are carried 

out separately for the samples selected 

from the landline and cell-phone sample 

frames. Second, in Steps 9 and 11, 

telephone status is added as an extra 

dimension to the raking adjustments.

Description of dual-frame 

estimation methodology, 

2011–2014

The dual-frame estimation 

methodology used for NIS–Child in 

2011–2014 followed the three major 

stages used in 2005–2010: 

1) derivation of annual household

weights, 2) derivation of child-level 

interview weights, and 3) derivation of 

provider-phase weights (Figure 8).

The dual-frame annual household 

weight

Annual household weights are 

derived separately within each sample 

(landline, cell phone), following the 

same six steps (Step 1–Step 6) described 

previously for the 2005–2010 weighting 

methodology. When deriving annual 

household weights for the cell-phone 

sample, appropriate adjustments are 

made to the weighting methodology. Cell 

phone sample nonresponse adjustment 

cells are defined by cross-classifying 

the census region and MSA status (in 

MSA, not in MSA), and adjustments are 

made to account for the number of links 

between the eligible child and cell-phone 

numbers used by the child’s parents in the 

household (52).

Child-level interview weights

Each age-eligible child in households 

with completed household interviews 

receives the survey weight for their 

household, with the second stage of 

weighting involving five steps all carried 

out within the estimation area. The first 

step (Step 7 in the overall weighting 

λa =

=

Var{ŶC(D)a}

Var{ŶL(D)a} + Var{ŶC(D)a}

nL(D)a

DEFFL(D)a

nL(D)a

DEFFL(D)a

nC(D)a

DEFFC(D)a

+
Page 22  Series 1, No. 61

methodology) is carried out separately by 

sample, with the remaining steps being 

carried out on the combined landline and 

cell-phone sample.

Step 7. Ratio adjustment to 

population totals by telephone status—

The annual household weights are 

adjusted to agree with independent 

estimates of the size of the population 

by telephone status, with adjustment to 

population estimates of the dual-user 

population made separately for the 

landline and cell-phone samples (with 

adjustment for the overlap conducted in 

the next step).

Step 8. Adjustment for combining 

landline and cell-phone samples—The 

landline-sampling frame covers children 

in dual-user households as well as 

children in LLO households, while the 

cell-phone sampling frame also covers 

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Child, 2011–2014.

 

Figure 8. Weighting flowchart for National Immunization Survey–Child, 2011–2014
Series 1, No. 61  Page 23 

children in dual-user households as 

well as children in CPO households. 

Compositing of the telephone statusadjusted weights for the landline and 

cell-phone sample cases is carried out as 

described previously, resulting in childlevel weights Wj

' .

Step 9. Attenuation of the CPO 

sample weights (2011 only)—An optimal 

balance of landline and cell-phone 

sample was not feasible in 2011 due 

to funding limitations. The cell-phone 

sample was relatively small, resulting in 

weights dramatically larger than those 

for the landline sample. The variability in 

the weights increased the variance of the 

estimated vaccination coverage rates. For 

2012, 2013, and 2014, cell-phone sample 

sizes were sufficiently large, and so this 

step of attenuation of the CPO sample 

weights was not applied.

Attenuation of the sample weights 

for CPO cases was utilized to minimize 

the MSE of estimates. Attenuation was 

achieved by compositing the direct 

estimator of the CPO domain total with 

an estimator of the same domain total 

derived from a subset of the landline 

sample deemed to be “similar” to CPO 

sample cases (and referred to as proxy 

CPO cases). The predicted probability 

of a landline sample case being 

similar to CPO cases was determined 

using a logistic-regression model for 

predicting a CPO status run on the full 

set of dual-frame sample cases (i.e., 

both landline and cell), and including 

both sociodemographic characteristics 

and vaccination status variables as 

explanatory variables.

Landline cases with a predicted 

probability above a determined cutoff 

level were classified as proxy CPO cases.

This compositing was carried out 

using adjustment factors based on the 

variance and bias associated with the 

component estimates. The resulting 

adjusted survey weights yield minimum 

MSE estimates. This adjustment was 

accomplished through the expression

ŶCPOa = κa ŶC(CPO)a + (1-κa) ŶL(Proxy CPO)a

where ŶC(CPO)a is the estimated total 

number of children in estimation area a

with the attribute of interest (e.g., UTD 

for the 4:3:1:3:3:1 vaccine series) based 

on children with completed interviews 

living in CPO households; ŶL(Proxy CPO)a is 

the estimated total number of children in 

estimation area a with the attribute of 

interest based on children obtained 

through the landline frame with 

completed interviews living in proxy 

CPO households; and the composition 

factor, κa, is

κa =

VLa + BLa

VCa + VLa + BLa

where VCa = Var {ŶC(CPO)a},

 VLa = Var{ŶL(ProxyCPO)a}, and

 BLa = Bias{ŶL(ProxyCPO)a}

 = E{ŶL(ProxyCPO)a – ŶC(CPO)a}

2

2

Adjustment of the weights for true 

and proxy CPO sample was then carried 

out in consideration of the empirical 

compositing factors

W"

j =

{1 + (1 – κ ' a )}Wj

 ,

 j ∈ L(Proxy CPO), a

ˆ

κˆ ' aWj , j ∈ C(CPO), a

W '

j

 , j ∈ L(D),

 j ∉ L(Proxy CPO)

W '

j

 , j ∈ C(D)

W '

j

 , j ∈ L(LLO),

 j ∉ L(Proxy CPO),

where κˆ a is a sample-based estimator of 

κa. More information about the overall 

estimation procedure, and specifically the 

attenuation procedure, is discussed in 

Wolter, et al (53).

Step 10. Ratio adjustment to 

estimation area population totals 

(2012–2014)—A simple poststratification 

scheme to reduce bias due to differential 

coverage was carried out in 2011, using 

the same approach as that described for 

the 2005–2010 weighting methodology 

(ratio adjustment to poststratification cells 

defined by mother’s race or ethnicity, 

mother’s educational attainment, and 

child’s age). This step was changed 

for 2012–2014 from a simple ratio 

adjustment to only estimation area overall 

population totals.

Within each estimation area, the 

poststratification cells are defined by the 

race or ethnicity of the child’s mother 

(Hispanic, non-Hispanic black alone, 

all other), educational attainment of the 

child’s mother (12 years or less, and more 

than 12 years), and age category of the 

child (19–23 months, 24–29 months, 

30–35 months). To control sampling 

variability, cells with fewer than 25 

children are collapsed with neighboring 

cells.

Step 11. Raking adjustment and 

trimming of poststratified child weights—

This step mirrors raking for the 2005–

2010 weighting methodology, with one 

additional raking dimension: telephone 

status. The 2011 weighting methodology 

used four categories of telephone status: 

LLO, dual-user, CPO, and phoneless. 

For 2012–2014, because of the small 

proportion of LLO and phoneless 

households containing children, two 

categories were used (CPO, other).

The survey weights resulting 

from Step 11 represent the child-level 

interview weights, and they are used to 

generate dual-frame child-level estimates 

for data collected in the household 

interview.

Provider-phase weights

Dual-frame provider-phase weights 

are derived following the same two steps 

described previously for the 2005–2010 

weighting methodology. For 2011 only, 

three additional steps were included 

between provider nonresponse 

adjustment (Step 12) and raking 

adjustment to population totals (Step 16). 

These steps were 1) adjustment to 

population totals by telephone status, 

2) adjustment for combining the landline 

and cell-phone samples (repeated to 

optimize estimates based on data from 

the PRC), and 3) attenuation of the CPO 

domain weights. With the implementation 

of optimal allocation across the landline 

and cell-phone samples, these three steps 

were deemed unnecessary for 

2012–2014. With the transition to a 

dual-frame sample design in 2011, 

additional variables (OWNER, TEL_

SAMPFRAME) were considered and 

included in the response-propensity 

model for provider nonresponse, along 

with interactions between TEL_

SAMPFRAME and other variables. 

Table 15 provides the list of additional 
Page 24  Series 1, No. 61

variables and shows which variables were 

selected each year.

The resulting survey weights 

represent the provider-phase weights, 

and they are used to generate dual-frame 

child-level estimates for data collected 

in the PRC, including estimates of 

vaccination coverage rates.

Population control totals by 

telephone status

With the inclusion of a cell-phone 

sample, more detailed population 

estimates by telephone status were 

needed for weighting the combined 

landline and cell-phone samples. Data 

from NHIS show that the percentage 

of children under age 18 years living in 

CPO households in the United States has 

grown from 4.9% in the second half of 

2004 to 47.1% in the second half of 2013, 

and those living in LLO households has 

decreased from 31.4% to 3.8% during 

this same period (22). Moreover, there is 

significant variation across states in the 

CPO estimates for children under age 18 

(51). 

NHIS is designed to produce 

national-level estimates but does not 

have a sufficient sample size to produce 

reliable, direct estimates at the NIS–

Child estimation-area level. In order 

to produce telephone status estimates 

at the estimation-area level, small-area 

modeling techniques are used to combine 

direct estimates for each telephoneservice-use category obtained from NHIS 

with auxiliary data from ACS to produce 

model-based estimates for children aged 

19–35 months and adolescents aged 

13–17. Initial model-based estimates are 

produced for the proportion of children 

under age 18 who lived in households 

that were CPO, cell-phone-mostly, dualuser, landline mostly, and LLO, following 

the methodology (51).

Because NIS–Child requires 

telephone status estimates for children 

aged 19–35 months, the annual estimates 

for children aged 0–17 years for each 

estimation area are adjusted using a 

multistep process. The annual estimates 

for children aged 0–17 years are ratio 

adjusted using NHIS estimates for 

children aged 1–2 years (used as an 

approximation for children aged 19–35 

months) at the census region level. Next, 

these adjusted estimates of proportions 

are calibrated so that they agree by 

estimation area with the most recent 

1-year ACS estimate for the proportion of 

children living in households with a 

telephone. These calibrated estimates are 

the final telephone status estimates. 

Finally, population control totals (Table 4) 

for children aged 19–35 months by 

estimation area and telephone status are 

obtained by multiplying these proportions 

by telephone status, times the population 

totals for children aged 19–35 months by 

estimation area, obtained using natality 

data from NCHS’ National Vital Statistics 

System (49). 

Ratio Estimator of the 

Vaccination Coverage 

Rate and the Taylor Series 

Estimator of Its Variance

Ratio estimator

Estimates of vaccination coverage 

in NIS–Child are weighted proportions 

of children who are UTD, often in some 

domain of interest (such as an estimation 

area or a racial or ethnic population). 

Formally, those proportions are ratio 

estimators, either within a sampling 

stratum (sampling frame by estimation 

area), or combining the data across strata. 

In this section, let L represent the 

number of sampling strata, Nh be the 

number of households in the population 

in stratum h, Mhi be the number of ageeligible children in household i of stratum 

h,

1, if the j th child in the (h,i)-th

household is UTD for a given

vaccine

0, otherwise,

Yhij =

and

1, if the j th child in the (h,i)-th

household is in the

domain of interest

0, otherwise.

δhij =

Letting

Yh = ∑ ∑ δhij Yhij

Nh Mhi

i = 1 j = 1

and

the true but unknown vaccination rate for 

the domain is

∑ L

h=1Yh

∑ L

h=1Th

θ =

Let nh be the number of households 

sampled in stratum h, mhi the number of 

age-eligible children in household i of 

stratum h, and Whij the final providerphase weight for the (h, i, j)-th child. 

Then, the combined ratio estimator of the 

vaccination rate for the domain of interest 

is given by

∑ L

h=1Ŷh

∑ L

h=1Thˆ θ

ˆ =

where

Ŷh = ∑ ∑ Whij δhijYhij

nh mhi

i = 1 j = 1

and

Th = ∑ ∑ Whij δhij 

nh mhi

i = 1 j = 1

ˆ

Taylor-series estimator of 

variance 

If any biases are small (due to the 

use of model-based population estimates 

by estimation area for calibration 

purposes and to any other measurement 

factor), then variance estimates can be 

used to make valid inferences to the 

population of age-eligible children. 

(Nonsampling errors and bias are 

discussed in “Assessment of Total Survey 

Error”.) To estimate the variance of θˆ , a 

Taylor-series approximation is used (54). 

Let

∑ nh

i=1 Zhi

nh

Zˉh =

Whij δhij (Yhij – θ ) 

∑ L

h=1Th

Zhij = ˆ

ˆ

and

Zhi = ∑ Zhij

mhi

j = 1

Th = ∑ ∑ δhij

Nh Mhi

i = 1 j = 1
Series 1, No. 61  Page 25 

then, the Taylor-series estimator of the 

variance of θˆ is (neglecting higher-order 

terms)

For NIS–Child, the crossing of 

frame (landline and cell phone) by 

estimation area serves as the sampling 

strata, while the household serves as the 

primary sampling unit. This estimator of 

variance is based on an assumption of 

with-replacement sampling of primary 

sampling units within strata, which 

closely mirrors the situation found 

in NIS–Child, because the sampling 

fractions of household primary sampling 

units within frame-by-estimation-area 

strata are generally quite small. 

Program code

Program code for estimating 

vaccination coverage rates and their 

standard errors using SUDAAN, SAS, 

and R are available in the NIS–Child data 

user’s guide (55).

NIS–Teen

Introduction

NIS–Teen, which targets the national 

population of adolescents aged 13–17, 

was launched in Q4/2006 and in Q4/2007 

(56,57). Annual data collection for the 

estimation areas began in 2008, for all 4 

quarters of the year, and continued 

through 2014. NIS–Teen uses a subsample 

of the telephone numbers selected for 

NIS–Child and the two-phase datacollection model of NIS–Child. (The 

household and provider surveys are 

closely modeled after the corresponding 

surveys used in NIS–Child.) Vaccines 

routinely recommended for adolescents 

and selected childhood catch-up vaccines 

are monitored in NIS–Teen (Table 2). As 

new vaccines are added to the Advisory 

Committee on Immunization Practices 

“Recommended Immunization Schedule 

for Children and Adolescents Aged 18 

Years or Younger” (available from: 

https://www.cdc.gov/vaccines/schedules/

hcp/child-adolescent.html), they are 

included in NIS–Teen data collection as 

soon as 2 calendar quarters after being 

added to the schedule. CDC first 

published the NIS–Teen estimated 

vaccination coverage rates in a 2007 

report (17); this report and additional 

publications are available from: https://

www.cdc.gov/vaccines/imz-managers/

coverage/teenvaxview/pubspresentations.html. Public-use microdata 

files for data analysis are available from: 

https://www.cdc.gov/vaccines/imzmanagers/nis/data-tables.html.

Sample Design

NIS–Teen was designed initially 

to achieve a nationally representative 

sample of 5,000 completed household 

interviews for adolescents in each of 

the years 2006 and 2007. For survey 

years 2008 and 2009, NIS–Teen was 

redesigned and expanded to produce 

state and local-area estimates to achieve 

180 effective completed interviews for 

adolescents with adequate provider data 

(APD) in each of the core 56 estimation 

areas defined for NIS and additional 

substate supplemental areas and U.S.- 

affiliated jurisdictions, as defined from 

year to year. In 2010–2014, the target 

sample size per estimation area was 

increased further to achieve a coefficient 

of variation (CV) of the estimated annual 

vaccination coverage rate of no more than 

6.5%, assuming the true coverage rate 

is 50%, which required approximately 

230 effective adolescents with APD per 

estimation area. The supplemental areas 

(beyond the core 56 areas) included 

in NIS–Teen varied from year to year 

and were not always the same as the 

supplemental areas included in NIS–

Child. 

In households with multiple 

adolescents, one age-eligible adolescent 

is selected at random to be the subject 

of the survey. This process differs from 

NIS–Child, which targets all children 

aged 19–35 months in the household. 

Since the eligibility rate in the population 

is much higher for adolescents aged 13–

17 than for children aged 19–35 months, 

the screening sample size requirements 

are smaller than what is required for 

NIS–Child. The required adolescent 

sample size per estimation area can 

generally be met utilizing a subsample of 

the NIS–Child RDD screening sample. 

Prior to 2011, the sampling for 

NIS–Teen was based on a subsample 

of the NIS–Child single-frame landline 

RDD sample. In Q4/2010, just as a 

small national cell-phone sample was 

piloted to assess and prepare for eventual 

integration of a cell-phone RDD sample 

with the traditional landline RDD 

sample for NIS–Child, a small national 

cell-phone subsample of the NIS–Child 

sample was piloted for NIS–Teen. 

See “Evaluation of NIS Estimates and 

Methods” for a description of this pilot 

study. In the 2011 NIS–Teen, a cell-phone 

RDD sample stratified by estimation 

area was fielded, and NIS–Teen became 

a dual-frame telephone survey. At that 

point, the cell-phone sample size within 

each estimation area remained relatively 

small. Beginning in 2012, a much larger 

and optimally allocated cell-phone RDD 

sample was introduced in NIS–Child. 

Correspondingly, NIS–Teen used a larger 

and near optimally allocated cell-phone 

sample starting in 2012 (31). In a few 

estimation areas, it was not possible 

to use a fully optimal allocation for 

NIS–Teen because children aged 19–35 

months tended to live in CPO households 

at a higher rate than adolescents aged 

13–17. A fully optimal allocation for 

NIS–Teen would require a larger sample 

size than NIS–Child provides.

NIS–Child 2006 completion rates 

were used to plan the sample size 

required for the 2006 NIS–Teen. The 

planning value of the eligibility rate 

for the 2006 NIS–Teen sample was 

determined by estimating the proportion 

of households with adolescents aged 

13–17, using the Current Population 

Survey for Q4/2006 and applying a 

conservative discount factor to ensure 

the sample drawn and prepared for NIS–

Teen fielding would be of sufficient size. 

Eligibility rates and completion rates 

for planning the 2007–2014 NIS–Teen 

sample sizes were determined using both 

NIS–Child and NIS–Teen actual rates 

from previous surveys. 

As noted, age-eligible adolescent 

households are generally more prevalent 

than age-eligible child households. The 

NIS–Teen sample size needed in the 

v(θ) = ∑

L nh

h = 1 i = 1

ˆ ∑ (Zhi – Zh) nh 2

nh – 1 ˉ
Page 26  Series 1, No. 61

telephone sampling frame to obtain the 

required number of completed household 

interviews at the estimation area level 

is generally, though not always, smaller 

than the sample size needed for NIS–

Child. For this reason, only a subsample 

of the telephone numbers released for 

NIS–Child are needed for screening to 

identify a sufficient sample of households 

with age-eligible adolescents. The 

subsampling rates are based on the ratios 

of the estimated sample sizes needed 

for NIS–Teen to those needed for NIS–

Child at the estimation-area level, and 

the telephone numbers chosen to be 

screened for adolescents aged 13–17 are 

randomly selected from the NIS–Child 

sample within each estimation area. At 

the national level in 2013, approximately 

70% of NIS–Child landline RDD sample 

telephone numbers and approximately 

85% of NIS–Child cell-phone RDD 

sample telephone numbers were needed 

to conduct NIS–Teen. The required 

numbers vary by estimation area, due to 

variation in area-specific eligibility and 

completion rates. In some estimation 

areas, 100% of the telephone numbers 

in the NIS–Child sample are needed 

for NIS–Teen. Sample release occurs 

continuously throughout a data-collection 

quarter and the fielding of the sample is 

monitored on a daily basis within and 

across quarters to assure the completion 

of the required number of household and 

provider interviews.

The data user’s guide for NIS–Teen 

contains additional information on the 

sample selection procedures (57).

NIS–Teen Survey 

Instruments

Similar to NIS–Child, the NIS–Teen 

household questionnaire contains a 

screening section to determine household 

eligibility (has at least one age-eligible 

adolescent), followed by the main 

household questionnaire administered 

only to eligible households. The NIS–

Teen screening section collects a roster 

of all age-eligible adolescents in the 

household, which is used to make a 

random selection of only one eligible 

adolescent from each household 

reporting multiple eligible adolescents. 

The standard sections included in the 

NIS–Teen household questionnaire are 

the same as for NIS–Child. The NIS–

Teen PRC questionnaire, known as the 

immunization history questionnaire 

(IHQ), collects information about the 

provider’s practice and the vaccination 

history of the selected adolescent. It has 

a similar structure, format, and content 

as the NIS–Child IHQ. The NIS–Teen 

household questionnaire and IHQ are 

available from: https://www.cdc.gov/

vaccines/imz-managers/nis/data-tables.

html. 

The NIS–Teen screening interview 

is conducted following all NIS–Child 

interviewing of the household. If the 

household is determined to be ineligible 

for NIS–Child, then the overall interview 

flows directly into the NIS–Teen 

screening interview and then to the NIS–

Teen main interview, if an age-eligible 

adolescent is identified. Otherwise, the 

NIS–Teen screening interview is delayed 

until after the NIS–Child main interview 

is completed. Approximately 3% of 

age-eligible and interviewed NIS–Child 

households are also age-eligible and 

interviewed for NIS–Teen each year.

Response Rates and Key 

Indicators 

As with NIS–Child, multiple 

indicators of survey progress and data 

quality are produced routinely for NIS–

Teen for each estimation area and at the 

national level both for the landline and 

cell-phone RDD samples in each datacollection year. These indicators include 

the resolution rate of released telephone 

numbers, the age-screening completion 

rate, and the interview completion rate. 

Key indicators for the landline RDD 

sample (Table 16), key indicators for the 

cell-phone RDD sample (Table 17), and 

response rates based on the combined 

landline and cell-phone RDD samples 

(Table 18) are presented below. 

Table 16 presents key indicators at 

the national level for data collection for 

Q4/2006, Q4/2007, and each year from 

2008 through 2014. For example, in the 

2013 landline RDD sample, 958,731 

telephone numbers were called via 

CATI to obtain estimates of vaccination 

coverage with predefined precision 

(CV is 6.5% or lower within each 

estimation area) for NIS–Teen. Among 

the identified households, 6.5% contained 

one or more age-eligible adolescents. 

The CASRO response rate was 51.1%. 

It can be calculated as the product of 

the resolution rate (83.5%), the agescreening completion rate (86.1%), and 

the interview completion rate among ageeligible households (71.1%). 

Table 17 shows that among the 

identified households in the cell-phone 

RDD sample in 2013, 6.7% contained 

one or more age-eligible adolescents. The 

2013 CASRO response rate was 23.3%. 

It is instructive to compare the ageeligibility rates in the two samples. In the 

landline sample (Table 16), the eligibility 

rate experienced a long-term decline—

from around 10% in 2006 to around 6% 

in 2014—due to the general migration 

of U.S. households from landline to 

CPO status. Meanwhile, eligibility was 

relatively stable in the cell-phone sample 

(Table 17), and the rate of eligibility—

around 7%—was slightly higher than the 

rate of eligibility in the landline sample 

by 2014.

For the PRC phase of NIS–Teen, 

Table 16 shows that interviews were 

completed for 10,148 age-eligible 

adolescents in the 2013 landline sample 

and lists the monitoring indicators for 

the PRC phase for those interviewed 

households. Specifically, 68.3% of 

household respondents provided consent 

to contact their adolescent’s vaccination 

providers. The number of IHQs mailed 

to vaccination providers was 11,659. 

This is greater than the total number of 

adolescents with consent because some 

adolescents had more than one nominated 

vaccination provider. In 2013, among 

adolescents with completed household 

interviews in the landline sample, 6,039 

(59.5%) were determined to have APD. 

In the 2013 cell-phone sample, among 

the adolescents with completed parental 

interviews, consent to contact vaccination 

providers was obtained for 65.0%, and 

APD were obtained for 54.5% of 

adolescents (Table 17).

The response rate for the combined 

NIS–Teen landline and cell-phone 

samples is defined as the total number of 
Series 1, No. 61  Page 27 

households with a completed adolescent 

interview, divided by the estimated total 

number of eligible adolescent households 

across both sample types, where the 

estimated total number of adolescent 

eligible households is equal to the sum 

of the estimated number of adolescent 

eligible households in the landline sample 

and the estimated number of adolescent 

eligible households in the cell-phone 

sample. Table 18 presents the response 

rates for the combined samples.

Trends in Key Indicators 

for NIS–Teen, 2006–2014

Trends in the CASRO response 

rate

Figure 9 displays the trends in key 

indicators of data-collection progress 

for NIS–Teen for each year from 2006 

through 2014 for the landline RDD 

samples (with 2006 and 2007 fielding 

only in Q4 of each year), excluding U.S. 

territories. The CASRO response rate 

(Table 16) rose from 56.2% in Q4/2006 

to 60.3% in 2014, with the lowest 

CASRO rate over the period occurring 

in 2013. Of the three completion rates 

contributing to the CASRO response rate, 

the resolution rate remained relatively 

stable during the period, the screening 

completion rate rose over the 9-year 

period, and the interview completion rate 

declined slightly, from 83.7% in Q1/2006 

to 71.1% in 2013 before rebounding 

to 83.8% in 2014. The rebound in the 

interview completion rate is attributed 

to the shorter NIS–Teen questionnaire 

introduced in 2014, which eliminated 

questions that gathered parental reporting 

of adolescent vaccinations. Part of the 

decline in the interview completion rate 

during the 2010–2013 period may be due 

to the inclusion of the Parental Attitudes 

topical module (see “Topical Modules”) 

and the addition of new vaccine-related 

questions for HPV and meningitis 

shots. Respondents were advised of 

longer administration times due to the 

inclusion of the additional topical module 

questions, which may in turn, have 

resulted in more interview break-offs. 

Trends in key indicators for the cellphone RDD sample for the 2011–2014 

period are presented in Figure 10. The 

CASRO rate increased from 22.4% to 

31.2% over the 4-year period, with the 

resolution and screening completion rates 

contributing to the upward trend. 

The broad movements in the 

combined response rate documented in 

Table 18 are the result of the changing 

composition of the two NIS–Teen 

samples. A relatively small cell-phone 

sample was added to NIS–Child and 

NIS–Teen beginning in 2011. In 2012 

and especially in 2013, the NIS surveys 

moved toward an optimum allocation 

of the overall survey resources, which 

resulted in a surge in the size of the 

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Teen, 2006–2014.

 

Figure 9. Trends in key indicators from household and provider data collections for National Immunization Survey–Teen: Landline 

random-digit-dialing sample excluding U.S. territories, 2006–2014 
Page 28  Series 1, No. 61

cell-phone sample starting in 2012 and 

increasing even more in 2013, and a 

corresponding decline in the size of the 

landline sample. The following year the 

surveys faced a budget restriction in 

2014, which forced use of a suboptimum 

allocation of the survey resources, 

resulting in an increase that year in the 

size of the landline sample and a decrease 

in the size of the cell-phone sample. The 

budget problem was temporary—by 

2015 and 2016, the cell-phone samples 

returned to their optimum sizes. For 

NIS–Teen, the landline response rate 

has generally been around twice the 

cell-phone response rate. Thus, as the 

size of the cell-phone sample increased 

(or decreased) from year to year, the 

combined response rate decreased (or 

increased). This pattern is evident in the 

lower combined response rate in 2013 

and the higher rate in 2014.

Trends in the number of 

advance letters mailed

To maximize response rates, advance 

letters are mailed to sample telephone 

numbers for which addresses are obtained 

using a reverse-match procedure. From 

Q4/2006 through Q4/2014, mailed 

advance letters, a percentage of telephone 

numbers released to CATI in the NIS–

Teen landline sample, steadily declined, 

from 59.1% to 40.4%. The decline is 

likely due to the declining WRN rate 

in the landline sample, as households 

increasingly have only cell phones (22). 

Advance letters were not used for the 

cell-phone RDD sample because mailing 

addresses were not available for cellphone numbers.

Trends in the percentage of 

adolescents with APD

The percentage of adolescents 

with APD in the landline RDD sample 

increased, from 52.7% in Q4/2006 to 

57.1% in 2014 (Table 16). The increase 

beginning in 2007 was mainly due to the 

IHQ return rate, which increased from 

89.2% in Q4/2006 to 94.9% in Q4/2014 

data collection. As the NIS–Teen PRC 

became integrated into the NIS–Child 

PRC operations, it benefitted from the 

best practices that had been established 

for NIS–Child. 

Potential limitations of APD 

Among adolescents for whom at 

least one identified vaccination provider 

returned the IHQ or medical records 

containing a vaccination history, a set of 

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Teen, 2011–2014.

Figure 10. Trends in key indicators from household and provider data collections for National Immunization Survey–Teen: Cell-phone 

random-digit-dialing sample excluding U.S. territories, 2011–2014
Series 1, No. 61  Page 29 

rules determined whether the adolescent 

was considered to have APD. From 

Q4/2006 through Q4/2013, these rules 

were as follows: 

● The adolescent was considered to 

have APD if the responding 

provider(s) reported the adolescent 

was UTD with the recommended 

number of doses of the following 

vaccines: 1 or more doses of Td/Tdap; 

3 or more doses of hepatitis B or 2 or 

more doses of 1.0 ml hepatitis B 

Recombivax; 2 or more doses of 

measles-mumps-rubella; and 1 or 

more doses of varicella vaccine or a 

history of chicken pox disease.

● The adolescent was also considered 

to have APD if the adolescent was 

UTD for the vaccines listed above 

when vaccinations after the date of 

the household interview were 

counted. 

● The adolescent was still considered 

to have APD unless the responding 

provider(s) reported fewer doses 

of the key recommended vaccines 

than the household respondent, in 

which case the adolescent was not 

considered to have APD. 

Beginning in 2014, the rules for 

classifying an adolescent as having APD 

in NIS–Teen were updated to coincide 

with the shortening of the NIS–Teen 

questionnaire in which most parental 

reporting of specific vaccinations was 

eliminated. The updated rules classify 

an adolescent as having APD if 1) one 

or more of the named providers report 

vaccination history data or 2) a parent 

and provider reports agree that the 

adolescent is completely unvaccinated.

The rules for an adolescent to be 

considered zero-shot (adolescent is also 

classified as having APD) are the same as 

for NIS–Child.

Among adolescents with APD, 

Figure 11 shows the trends in the 

percentage of adolescents with two or 

more providers from Q4/2006 to Q4/2014 

in the landline sample, excluding U.S. 

territories. This percentage increased 

slightly over the 2006–2009 period, 

ranging between 37% and 40%, before 

increasing to more than 50% in 2010–

2014. 

The increase was due to a household 

questionnaire change. When respondents 

were asked to identify the adolescent’s 

vaccination providers, beginning in 

Q1/2010, they were specifically asked to 

include hospitals, school and workplace 

clinics, juvenile detention centers, 

and emergency rooms, resulting in an 

increase in the number of providers 

identified per adolescent. Figure 11

also shows, among adolescents with 

APD and two or more providers, the 

percentage that have some, but not all 

providers reporting. This rate was 65.0% 

in Q4/2006 and 66.5% in Q4/2007 and 

dropped slightly to 62.0% by 2014. The 

decrease beginning in 2008 reflects the 

higher IHQ return rates beginning that 

year.

Vaccination records for a given 

adolescent may be scattered across 

the offices of the various providers 

who have seen the adolescent. An 

adolescent’s vaccination history may 

be established incompletely for one 

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Teen, 2006–2014.

Figure 11. Trends in percentages of adolescents with two or more providers among adolescents with adequate provider data, and 

adolescents with one or more providers not reporting among adolescents with adequate provider data and two or more providers, for 

National Immunization Survey–Teen: Combined landline and cell-phone random-digit-dialing samples excluding U.S. territories, 2006–2014
Page 30  Series 1, No. 61

or more vaccines, depending on the 

completeness of the reported set of 

providers available to include in the PRC, 

whether providers respond to the PRC, 

and whether the reported information 

indicates that the adolescent is not 

UTD with recommended vaccinations. 

Compiling an incomplete vaccination 

history due to record scattering has 

been shown to exist for children aged 

19–35 months (37,38). Furthermore, in 

NIS–Child, the gathering of vaccination 

history has been shown to differ by 

sociodemographic characteristics, 

including race and ethnicity (40). The 

potential for incomplete gathering of 

some adolescents’ vaccination histories 

from Q4/2006 to Q4/2014 due to record 

scattering may have impacted which 

adolescents in NIS–Teen were deemed to 

have APD, since the rules relied heavily 

on provider-reported vaccination statuses. 

Users of NIS–Teen data are cautioned to 

consider whether differences observed 

in vaccination coverage rates between 

sociodemographic and geographic 

subpopulations may, at least in part, be 

attributed to differences in incomplete 

gathering by subpopulation. 

Estimation Methodology

Vaccination coverage rate estimates 

and corresponding variance estimates 

for NIS–Teen are produced for each 

estimation area, each state, and the 

country once a year in May (in June, 

prior to 2014). The annual estimates 

include data collected in the Q1–Q4 

surveys from the previous calendar year. 

NIS–Teen followed similar dataprocessing steps and editing procedures 

as those used by NIS–Child for merging 

the household and provider data, 

determining the most accurate date of 

birth, and synthesizing the vaccination 

histories from possible multiple provider 

reports to determine whether the 

adolescent had APD. Missing values in 

variables necessary for creating sampling 

weights were imputed using hot-deck 

imputation methods, as described for 

NIS–Child. These variables included 

the adolescent’s sex; number of landline 

telephone numbers in the household; 

mobility status; household income; and 

demographic variables, such as maternal 

marital status, maternal education, race, 

ethnicity, and maternal age. 

The weighting procedure for the 

NIS–Teen annual landline sample 

accounts for variation in sampling 

rates, differential response rates, and 

differential sample-frame undercoverage, 

and it mirrors the multistep weighting 

procedure used for NIS–Child, with one 

difference. The NIS–Teen procedure 

includes an additional step after adjusting 

for nonresponse to the age-eligibility 

screener: to multiply the emergent weight 

by the number of eligible adolescents in 

the household as a means of accounting 

for the random selection of one 

adolescent per household. 

Two final weights are calculated 

annually for NIS–Teen: an RDD-phase 

weight to analyze household-reported 

data and a provider-phase weight to 

analyze provider-reported data. The set of 

adolescents with APD and their weights 

are then used to tabulate vaccination 

coverage rates for publication in reports, 

journals, and on CDC’s TeenVaxView 

website (available from: https://www.cdc.

gov/vaccines/imz-managers/coverage/

teenvaxview/data-reports/index.html).

Figure 12 and Table 19 provide the 

estimated percentages of adolescents by 

telephone status within estimation areas 

that were used to provide population 

control totals in the dual-frame weighting 

procedure for the 2013 NIS–Teen data. 

The data user’s guide for NIS–Teen 

contains additional information about the 

estimation methodology (57).

Topical Modules

Introduction

From the inception of NIS–Child 

in 1994, its primary purpose has been 

to provide data to estimate vaccination 

coverage rates for specified local 

geographic areas, the 50 states and 

the District of Columbia, and the 

United States. In addition, the survey 

collects child, maternal, and household 

characteristics to identify and track 

disparities in vaccination coverage 

associated with those factors, and to 

track progress in achievement of Healthy 

People vaccination coverage objectives 

(58). 

In 2001, “topical modules” were 

added to NIS–Child to provide further 

information about financial barriers to 

vaccinations, VFC, parental concerns 

about vaccines as a barrier to becoming 

vaccinated, the effect of vaccine 

shortages, and the use of NIS–Child as 

a sampling frame for data collection on 

other childhood and maternal topics. 

From 2001 through 2014, a wide array of 

topical modules were added to NIS–Child 

and NIS–Teen. Although topical modules 

are most commonly administered as 

additional questionnaires within the 

NIS–Child or NIS–Teen interviews 

and to all household respondents, they 

were also conducted as separate followup surveys to previous respondents or 

offered to a subset of survey respondents 

at the time of the NIS–Child or NIS–Teen 

interviews. 

This section provides a synopsis 

of the topical modules conducted from 

2001 through 2004 and more in-depth 

descriptions of the topical modules 

conducted from 2005 through 2014. 

Table 20 gives a quick summary of these 

modules. 

NIS–Child Knowledge, 

Attitudes, and Practices 

Module 

The first topical module 

administered was the Knowledge, 

Attitudes, and Practices (NIS–KAP) 

module. Its objective was to determine 

how parental knowledge and attitudes 

and health care provider’s attitudes and 

practices affected children’s vaccination 

status. Conducted in 2001 as a follow-up 

interview of households that participated 

in the 2000–2001 NIS–Child, NIS–KAP 

was designed to collect data on parents’ 

concerns about vaccinating their children. 

Upon consent from the parents, a mail 

survey was sent to children’s providers 

asking questions about provider attitudes 

and practices. Published results from 

the NIS–KAP study documented the 

prevalence of parents who sought 

medical attention for a child due to an 

adverse event following immunization, 
Series 1, No. 61  Page 31 

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Teen, 2013.

 

Figure 12. Percentage of adolescents aged 13–17 in the population, by telephone status within estimation area, 2013
Page 32  Series 1, No. 61

and vaccine-related attitudes and beliefs 

of parents who sought medical attention 

for a child after an adverse event 

following immunization (59).

Concurrent Modules, 

2001–2002

NIS–Child added three topical 

modules and conducted them 

concurrently between Q3/2001 and 

Q4/2002 using a split sampling design 

(21). Those modules were the Health 

Insurance and Ability to Pay for Vaccines 

Module (HIM); Parental Knowledge 

and Experiences Module (PKM); and 

Daycare, Breastfeeding Practices, and 

WIC Module (DCM) (available from: 

https://www.cdc.gov/nchs/data/nis/

nisdug01.pdf). 

The purpose of HIM was to provide 

information on economic and health 

insurance-related barriers to vaccinations, 

to evaluate how those barriers were 

associated with vaccination coverage 

levels, and to provide information on 

vaccination coverage levels for children 

who were entitled to the VFC Program 

(60–62). The PKM aimed to provide 

further information on how parental 

concerns about vaccine safety affected 

vaccination coverage (63–68). Data from 

the DCM were collected to evaluate the 

vaccination status of children aged 19–35 

months who were enrolled in the Women, 

Infants, and Children (WIC) Program 

(69). These data were precursors for a 

series of questions now part of the routine 

NIS–Child that assess breastfeeding 

practices and WIC participation 

(available from: https://www.cdc.gov/

nchs/data/nis/nisdug01.pdf).

Vaccine Shortage and 

Vaccine Safety Modules

Two new topical modules were 

conducted from Q2/2003 through 

Q4/2003: Vaccine Shortage Module 

and Vaccine Safety Module (available 

from: https://www.cdc.gov/nchs/data/

nis/nisdug04.pdf). Data from the 2003 

Vaccine Shortage Module were used to 

evaluate the effects of shortages at that 

time of the pneumococcal vaccine (70), 

while data from the 2003 Vaccine Safety 

Module were used to show how parents’ 

concerns about vaccine safety might 

be moderated to achieve high levels of 

vaccination coverage (71). 

Influenza Module

NIS–Child conducted an Influenza 

Module from Q1/2004 through Q4/2004, 

and data were used in unpublished 

analyses of seasonal influenza coverage 

rates. 

Revisions to HIM 

HIM was revised in 2005 to conform 

to changes in insurance questions used 

in NHIS. NIS–Child introduced the 

revised module in 2006. Since then, HIM 

is asked of sampled households that 

complete sections A–D of the NIS–Child 

telephone interview, and is administered 

in English, Spanish, and other languages 

via Language Line Services (available 

from: ftp://ftp.cdc.gov/pub/Health_

Statistics/NCHS/Dataset_Documentation/

NIS/NISPUF07_DUG.pdf). HIM was 

included as section E of the NIS–Child 

household interview questionnaire 

starting in 2006, available from: ftp://ftp.

cdc.gov/pub/Health_Statistics/NCHS/

Dataset_Documentation/NIS/NISPUF13_

HHQuex.pdf. In 2006, 29,880 children 

had a completed household interview. 

Among these children, 24,712 completed 

HIM, resulting in a completion rate of 

82.7%. 

The HIM data enabled researchers 

to determine whether sampled children 

are covered by private insurance, public 

insurance (Medicaid or their state’s 

Children’s Health Insurance Program), 

military insurance (TRICARE), or the 

Indian Health Service. The HIM data 

were used to identify children entitled 

to receive publicly purchased vaccines 

through their state’s VFC Program at 

the time of the NIS–Child telephone 

interview. The VFC Program helps 

provide vaccines to children whose 

parents or guardians may not be able to 

afford them. Children are eligible for the 

VFC Program if they are under age 19 

years and are on Medicaid, uninsured 

(not covered by health insurance), 

underinsured (insurance does not 

cover vaccines or covers only selected 

vaccines), or American Indian or Alaska 

Native persons. Underinsured children 

are eligible to receive VFC vaccines only 

at federally qualified health centers or 

rural health clinics. 

CDC policy analysts have used data 

from NIS–Child and HIM to provide 

information about the percentage 

of children who are entitled to VFC 

vaccines and about the needs of the 

317 Immunization Grant Program 

(72). Section 317 of the Public Health 

Service Act provides federal funding 

to state, local, and territorial public 

health agencies for program operations 

and vaccine purchase. Section 317 

program funds also are used to support 

infrastructure functions, such as 

vaccine effectiveness studies, disease 

surveillance, outbreak detection and 

response, vaccine coverage assessment, 

vaccine safety, and provider education 

programming. 

Peer-reviewed publications written 

by CDC staff using HIM data have 

focused on vaccine financing issues 

related to underinsured children (73) and 

on vaccination coverage among VFCentitled children (74).

HIM for NIS–Teen

Since 2006, NIS–Teen has included 

the HIM questions from NIS–Child, 

enabling the same determinations to be 

made regarding insurance coverage and 

VFC eligibility for adolescents aged 

13–17. The 2013 household questionnaire 

is available from: ftp://ftp.cdc.gov/

pub/Health_Statistics/NCHS/Dataset_

Documentation/NIS/NISteenPUF13_

HHQuex.pdf. In 2006, 5,468 adolescents 

had a completed household interview. 

Among them, 4,356 completed HIM, 

resulting in a completion rate of 79.7%. 

A peer-reviewed publication written 

by CDC staff using HIM data from 

NIS–Teen focused on vaccine financing 

issues related to underinsured adolescents 

(75) and on vaccination coverage among 

VFC-entitled adolescents.
Series 1, No. 61  Page 33 

Socioeconomic Status 

Module 

The Socioeconomic Status (SES) 

Module was developed to assess the 

contributions of socioeconomic factors to 

racial, ethnic, and economic disparities 

in vaccination coverage. Questions were 

developed to measure factors, such as 

household education level, maternal 

employment status, home ownership or 

rental, car ownership, child’s general 

health status, experience with regular 

doctor or office for medical visits, travel 

time to doctor’s office, wait time in 

doctor’s office, and routine use of child 

daycare services. Adding these types 

of questions to NIS–Child provided 

researchers with additional tools to 

determine how socioeconomic factors 

influence vaccination coverage and 

to develop more targeted strategies to 

address racial and ethnic and economic 

disparities in childhood vaccination. 

The SES module was conducted in 

households with age-eligible children 

in Q1/2008 and Q2/2008. Administered 

immediately after HIM, the SES 

module was also translated into Spanish 

and conducted in other languages by 

use of Language Line Services. The 

SES module was designed to gather 

household-level data, child-level data for 

each eligible child in the household, and 

data for the maternal primary caregiver. 

Where no maternal primary caregiver 

was available, data were gathered for the 

paternal primary caregiver. 

A total of 11,102 children had a 

completed household interview and were 

flagged to receive the SES module. Of 

those, 8,768 had a completed module, 

resulting in a completion rate of 79.0%; 

7,450 children had both a completed 

module and adequate provider-reported 

vaccination data. Data from the SES 

module have been used to explore how 

employment and socioeconomic factors 

are associated with children’s UTD 

vaccination status (76). 

NIS–Child Parental 

Concerns Module and NIS–

Teen Parental Attitudes 

Module

In February 2006, the National 

Vaccine Program Office (NVPO) 

Subcommittee on Public Engagement 

expressed concerns about the lack of 

detailed surveillance on public concerns 

and knowledge about vaccine safety and 

acceptance. In 2007 and 2008, NVPO 

funded a proposal to develop a new 

parental concerns topical module for 

NIS–Child that would collect data over 4 

consecutive quarters. The structure of the 

survey questions in the Parental Concerns 

Module (PCM) was based on the 2001–

2002 PKM described previously, and 

included sections on parents’ perceptions 

about vaccines, their satisfaction with 

their experience getting their child 

vaccinated, influences on their decisions 

to vaccinate their child, and vaccine 

delay or refusal. Starting in Q3/2008 and 

continuing through Q4/2009, PCM was 

incorporated as Section F of the NIS–

Child household questionnaire (available 

from: ftp://ftp.cdc.gov/pub/Health_

Statistics/NCHS/Dataset_Documentation/

NIS/NISPUF09_HHQUEX.pdf). 

Questions from PCM were 

administered to parents completing the 

NIS–Child telephone interview. From 

Q3/2008 through Q4/2009, 38,248 

children completed the household 

interview and were flagged for the PCM; 

29,509 children also completed the PCM, 

resulting in a completion rate of 77.2%. 

Additionally, 24,875 children had both 

a completed PCM and APD available to 

evaluate sampled children’s providerreported vaccination status. The PCM 

was conducted again in 2011. 

Data from the 2009 PCM 

characterized parents’ psychosocial 

attitudes in terms of a behavioral 

model that was developed during the 

1950s polio epidemic by Rosenstock, 

Derryberry, and Carriger at the U.S. 

Public Health Service to explain why 

parents failed to vaccinate their children 

with the salk polio vaccine (77). Their 

findings, published in the journal 

Public Health Reports as the basis 

for the Health Belief Model, showed 

there were four psychosocial domains 

that influenced parents’ decisions to 

vaccinate their children. These domains 

were 1) susceptibility (their assessment 

of their child’s risk of getting polio); 

2) seriousness (their assessment of 

whether polio was a sufficient health 

concern to warrant vaccination); 3) 

efficacy and safety (their assessment 

of whether vaccinating their child can 

reduce the chances of getting polio, 

and whether the vaccine is safe); and 4) 

social pressures and convenience (the 

concerns and influences that facilitated 

or discouraged their decision to get their 

child vaccinated) (78–85). 

Data from the 2009 NIS–PCM have 

been used to investigate psychosocial 

factors that influence parental vaccination 

decisions for infants; to assess the 

prevalence of reported refusal or delay 

of vaccination among parents of children 

aged 19–35 months; and to assess how 

the psychosocial factors that index the 

Health Belief Model are associated with 

parental refusal or delay of vaccinations, 

and coverage for recommended 

childhood vaccines (86).

Funding from the American 

Recovery and Reinvestment Act 

(ARRA) of 2009 was used to develop 

and implement a Parental Attitudes 

Module (PAM) for NIS–Teen. ARRA 

funding was sufficient to allow data 

collection for PAM in NIS–Teen for 

Q3/2010 and Q4/2010. The structure of 

the survey questions was based on the 

NIS–Child PCM and sections on parents’ 

perceptions about vaccines, influences 

on parents’ decision to vaccinate their 

adolescent, and vaccine delay or refusal. 

The NIS–Teen PAM was incorporated 

as Section F of the 2010 NIS–Teen 

household questionnaire. A total of 

15,438 adolescents had a completed 

household interview and were flagged to 

receive PAM. Of those, 10,808 completed 

the module, resulting in a completion 

rate of 70.0%; 8,490 adolescents had 

both a completed module and adequate 

provider-reported vaccination data. 

Data from the 2010 NIS–Teen PAM 

have been used to investigate factors that 

influence parental vaccination decisions 

for adolescents (87,88), assess the 

prevalence of reported refusal or delay of 
Page 34  Series 1, No. 61

vaccination among parents of adolescent 

girls aged 13–17, and assess the 

relationship between refusal or delay of 

vaccination and coverage for HPV (89). 

Data from the 2011 NIS–Child PCM 

and 2010 NIS–Teen PAM were used to 

evaluate the extent to which children 

and adolescents in the United States 

are not vaccinated against measles. 

(90). A total of 18,633 children had a 

completed household interview and 

were eligible to receive the PCM. Of 

those, 13,921 had a completed module, 

resulting in a completion rate of 74.7%; 

12,259 children had both a completed 

module and adequate provider-reported 

vaccination data. Results showed that 

in 2011, 7.5% of children and 4.5% 

of adolescents were unvaccinated 

against measles; 80.0% of unvaccinated 

children lived in counties containing 

41.9% of the country’s children; and 

80.0% of unvaccinated adolescents 

lived in counties containing 30.4% of 

the country’s adolescents. Multivariable 

statistical analyses found that 74.6% 

of children who were unvaccinated 

against measles were not vaccinated 

for reasons other than parents’ negative 

vaccine-related beliefs, and 89.6% had 

at least one missed opportunity for being 

vaccinated against measles because 

they were administered at least 1 dose 

of other recommended vaccines after 

age 12 months. Among adolescents, 

multivariable analyses found that only 

demographic factors, and not vaccinerelated parental beliefs, were associated 

with being unvaccinated.

Quality Assurance and 

Data Dissemination 

Introduction 

NIS maintains dedication to the 

quality of the survey data throughout 

all of its phases, including sample 

design, questionnaire development, data 

collection, data processing, derivation 

of weights and estimates, data delivery, 

and dissemination. The ultimate goal 

is to provide reliable and actionable 

surveillance of childhood and adolescent 

vaccinations. 

The NIS approach to quality 

assurance consists of specific 

processes that provide assurance of 

three dimensions of quality: accuracy, 

timeliness, and accessibility to 

researchers. Quality assurance procedures 

were implemented consistently and 

continuously across all years of data 

collection and throughout every phase 

of NIS. In what follows, this report 

highlights the specific quality assurance 

procedures used in both NIS–Child and 

NIS–Teen, including those implemented 

throughout household data collection, 

PRC data collection, data processing, 

and production of final data files. 

Confidentiality, disclosure avoidance, 

and the commitment to accessibility 

and timely data dissemination are also 

discussed.

The quality assurance procedures 

implemented in NIS–Child from 1994 

through 2000 have been described 

previously (91). Their use has continued 

in the NIS family of surveys throughout 

2001–2014. To avoid repetition, this 

report focuses on additional quality 

assurance procedures and enhancements 

since 2005 and provides additional 

details regarding procedures described 

previously.

Quality Assurance 

Procedures

All surveys, including NIS, are 

subject to two types of error: sampling 

and nonsampling. Sampling errors are 

typically a function of the survey’s 

sample design and affect the variability 

of survey estimators. Nonsampling 

errors are the result of sample frame 

undercoverage, nonresponse, and 

measurement problems, and may 

introduce bias into survey estimators. 

Methodological responses to the 

problems of sample undercoverage and 

nonresponse bias have been described 

in previous sections of this report. This 

section focuses on quality assurance 

procedures to monitor and reduce 

measurement errors. These errors may 

arise due to problems in data collection, 

transcription, or editing. 

Household data collection

The household survey phase of NIS–

Child and NIS–Teen consists of sampling 

of telephone numbers, sample preparation 

and management, household survey 

instrument preparation and testing, 

training of interviewers, and computerassisted telephone interview (CATI) data 

collection by telephone interviewers.

Sample preparation—This step 

includes the selection of sample 

telephone numbers, the preparation 

of addresses for mailing letters to 

households matched to sampled 

telephone numbers, and the preparation 

of sampled telephone numbers for dialing 

in the CATI system. Routine monitoring 

by a team of NIS professionals helps 

identify potential quality issues in sample 

preparation. Additional quality assurance 

steps during these procedures include:

● Comparing prefinalization 

(i.e., resolution of telephone numbers 

as nonworking, nonresidential, or 

residential by the sample vendor 

prior to dialing) rates to prior years

● Comparing address matching rates 

with prior years

● Reviewing the frequencies of all 

variables loaded into the CATI system, 

comparing the frequencies of these 

variables with their corresponding 

values in previous quarters, and 

identifying any potentially invalid 

values

Sample management—This step 

includes monitoring the performance 

of the sampled telephone numbers that 

have been released into the CATI system, 

determining a schedule for the release 

of additional sample lines, and releasing 

additional sample lines as determined. 

Additional quality assurance steps during 

these procedures include:

● Continuous monitoring of the 

difference between projected and 

actual numbers of cumulative 

completed interviews

● Monitoring the landline and cellphone samples separately to assess 

differences in and issues with 

expected response rates, ageeligibility rates, and completion 

targets
Series 1, No. 61  Page 35 

Household survey instrument 

preparation and testing—Questionnaires 

and advance letters are thoroughly tested 

before use. Additional quality assurance 

procedures include:

● Testing of questionnaires by NIS 

interviewers using test samples

● Programming English and Spanish 

versions of the questionnaire in the 

CATI system to aid accessibility 

The CATI system and data collection 

by telephone interviewers—The CATI 

system incorporates a number of features 

designed to assure the quality of the 

household interview data, including:

● Programmed range and consistency 

checks to prevent entry of invalid 

or inconsistent responses to 

questionnaire items (e.g., the child’s 

date of birth is verified multiple 

times during the interview to ensure 

the correct date is used to initiate the 

provider phase)

● Advance testing to ensure proper 

questionnaire flow (i.e., appropriate 

questionnaire items are presented 

in the appropriate order and 

unnecessary items are skipped) 

● Regular review of the interview data 

by professional staff members to 

inspect item response distributions 

and reveal potential questionnaire 

errors

Catching potential errors early 

increases the efficiency of postsurvey 

data cleaning and processing. Outof-range and inconsistent responses 

produce a warning screen, allowing the 

interviewer to correct errors in real time. 

Warning screens focus on items critical to 

the survey, such as those that determine a 

child’s eligibility (e.g., date of birth).

In addition to the quality assurance 

safeguards in the CATI system, 

interviewers receive extensive and 

ongoing training.

● Interviewers undergo consistent, 

in-depth training and certification 

and are monitored and evaluated by 

supervisory staff.

● Supervisors act in real time to assist 

interviewers and identify and solve 

problems with the survey.

● Interviews are recorded, facilitating 

review by supervisors and 

methodology experts who can 

identify inefficiencies and translate 

this knowledge into questionnaire 

revisions. 

Quality assurance for PRC data 

collection

Vaccination histories are collected 

from vaccination providers identified 

during the household interview. The 

PRC process consists of transferring 

questionnaire data for each child-provider 

pair from the CATI system into the 

PRC case management system, locating 

provider addresses and mailing IHQs to 

providers, reviewing the returned IHQ 

or medical record data, and editing, 

transcribing, and entering data.

Transferring household 

questionnaire data and generation of the 

IHQ documents—Data from completed 

telephone interviews are transferred 

from the CATI system into the PRC 

case management system, which is 

the software and database system that 

controls PRC data-collection operations. 

Child-provider pairs identified in the 

telephone interview are checked for 

comprehensive and accurate information. 

They are also checked to verify that all 

steps were successfully completed, for 

complete transfer of data from CATI 

to the PRC case management system, 

duplicate cases, missing information 

on children and providers, and valid 

signatures by interviewers verifying that 

consent to contact medical providers 

was obtained. Next, IHQ documents are 

generated electronically for mailing to 

providers. The PRC staff reviews these 

new cases weekly before the mailing 

to ensure that documents are generated 

correctly for both initial mailings and 

remailings. Additional quality assurance 

steps include:

● Checking contact information for 

each child’s nominated providers for 

identifying duplicates and deleting 

any verified duplicates

● Reviewing cases with missing or 

incomplete child name or consentgiver name or provider address, and 

making repeat calls to obtain the 

missing information

● Checking that all consent forms were 

signed by interviewers and correctly 

attached during document generation 

Locating provider addresses and 

mailing IHQs to providers—During 

this process, the PRC production team 

seeks a complete and accurate mailing 

address and telephone number for 

health care providers identified during 

the household interview. A database of 

collected provider information, available 

in real time to the telephone interviewers, 

improves the accuracy and efficiency 

in identifying and locating providers. 

The PRC production team reviews IHQ 

documents that have been generated and 

assembled prior to mailing the packages 

to the located providers. Additional 

quality assurance procedures include:

● Review of the mailing addresses for 

proper U.S. Postal Service address 

formatting, spelling, and matching of 

city, state, and ZIP code

● Use of two tiers of locating staff, 

distinguished by proven experience 

and skill, with the upper-tier clerks 

reviewing cases lower-tier clerks 

were unable to locate

Review, editing, transcription, and 

data entry—Returned IHQs may require 

editing, and some providers return a 

copy of the original medical records 

rather than a completed IHQ. During 

the editing and transcription process, the 

PRC production team transcribes any 

medical records onto an IHQ, checks for 

data consistency, and converts data to 

specified codes in preparation for data 

entry. The data are then entered into the 

PRC database. Specific checks on data 

items are implemented, and cases with 

inconsistencies are flagged for manual 

review to determine if any corrections 

need to be made. Additional quality 

assurance steps include:

● Medical records and the IHQ 

responses are edited to conform with 

prespecified date, number, and name 

formats to ensure consistency in the 

PRC data

● IHQ data are double-keyed into the 

provider database, and discrepancies 

are manually reviewed to ensure 

accurate data entry
Page 36  Series 1, No. 61

● All keyed data are examined for a set 

of predetermined data entry errors, 

including inconsistent name or sex; 

missing, invalid, or inconsistent 

vaccination dates; or inconsistent 

responses 

● Electronic PRC data records with 

potential errors are compared with 

original paper IHQs to identify 

corrections as needed 

The period 2005–2014 has seen 

an increased tendency by providers to 

send copies of medical records in lieu 

of returning completed IHQs. This trend 

has both positive and negative quality 

implications. Original medical records 

are assumed to be the gold standard 

for vaccination information, yet these 

data must be transcribed onto IHQs by 

PRC production staff, which carries the 

potential for error. However, transcription 

must be accomplished somehow, either 

by an employee at the medical provider’s 

office completing the IHQ or by an 

NIS PRC staff member transcribing 

information from the medical record onto 

the IHQ. To improve the quality of the 

latter transcriptions, PRC staff members 

are trained to read and understand 

medical records and to transcribe 

them correctly, though the additional 

time needed to transcribe and apply 

quality assurance procedures may have 

implications for timeliness. Considering 

all of this, allowing providers to respond 

by sending medical records is viewed 

positively because it gives providers 

an alternative method of response and 

increases the provider cooperation rate. 

Every quarter since 2005, for both 

NIS–Child and NIS–Teen, data from a 

10% sample of IHQs are double-keyed 

into the IHQ database a second time, and 

the results are compared with the original 

double-keying as a basis for measuring 

the rate of data entry errors in the PRC. 

The error rate is defined as the number 

of fields for which the initial data entry 

does not match the second data entry, 

divided by the total number of fields with 

a nonblank value in either the initial or 

second data entry. The keying error rates 

in NIS–Child have declined steadily since 

2005 and reached their lowest levels in 

2014, averaging just 0.16% among all 

fields and 0.08% among numeric fields. 

The keying error rates have also steadily 

declined for NIS–Teen, reaching lows of 

0.16% among all fields and 0.09% among 

numeric fields in 2013. Figure 13 and 

Figure 14 display the IHQ keying error 

rates since 2005 for NIS–Child and since 

2006 for NIS–Teen.

Quality assurance for data 

processing

Following data collection, the 

household and provider data are 

reviewed, edited, and combined to 

create an analytic data file containing a 

record for each child with a completed 

household interview. This phase includes 

post-CATI cleaning and editing of the 

household-level data; cleaning, editing, 

and de-duplication (i.e., removal of 

duplicate vaccinations that occurs when 

the same vaccination is reported in 

two provider records) of the provider 

vaccination data; merging the household 

and provider data for the same child; 

“matching sheet” review to determine 

the best synthesized vaccination history 

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Child, 2005–2014.

Figure 13. Immunization history questionnaire keying error rates for National Immunization Survey–Child, 2005–2014
Series 1, No. 61  Page 37 

for each child; derivation of composite 

variables; and imputation of missing 

values.

To facilitate consistency and 

transparency in data processing, this 

work is organized into six distinct 

steps (see Table 21), each of which is 

thoroughly documented with detailed 

specifications. This approach ensures that 

these important steps occur in the proper 

order and in a timely manner. These 

standard steps clarify the process and 

increase efficiency as multiple members 

of the NIS data-processing team work 

with the survey data. Regular review and 

quality assurance occurs at each step of 

the process.

Post-CATI data editing and 

summarization (Step 1)—The postCATI editing process produces final, 

cleaned data files for each quarter. 

After completion of household 

interviewing each quarter, the raw data 

are extracted from the CATI system 

and used to create two files: the sample 

file and the interview data file. The 

sample file contains one record for 

each sample telephone number and 

summary information for telephone 

numbers and households. The interview 

data file contains one record for each 

eligible sample child or adolescent 

and all vaccination data the household 

respondent reported for the child or 

adolescent. 

Following creation of these two 

files, a preliminary analysis of each 

file identifies out-of-range values and 

extraneous codes. Invalid values are 

replaced with either an appropriate 

data value or a missing value code. The 

eligibility statuses of the children and 

adolescents, based on date of birth and 

date of interview, are checked. Ageineligible cases are deleted. 

After the computer edits are run, 

frequency distributions of all variables 

in each file are produced and manually 

reviewed. Each variable's range of values 

is examined for any invalid values or 

unusual distributions. If blank values 

exist for a variable, they are checked to 

determine whether they are allowable and 

whether they occur in excessive numbers. 

Skip-logic tests ensure that all data fields 

are populated correctly when they should 

be, and not populated when they should 

not be. Any problems are investigated 

and corrected as appropriate. 

Computer programs check that cases 

exist in both files in a consistent manner. 

Checks also ensure that no duplicate 

households exist in the sample file and no 

duplicate children exist in the interview 

data file.

IHQ data processing (Step 2)—After 

the majority of the IHQs have been 

collected from providers and keyed, the 

provider data file is cleaned in a similar 

fashion to the household data file in terms 

of out-of-range values and consistency 

of the values of different associated 

variables. A computer program codes all 

“other shot” verbatim responses into the 

proper vaccine category (e.g., Engerix B 

counts as HepB, and Tetramune counts 

as DTP and Hib). The coding for a 

new quarter uses a database of coded 

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Teen, 2006–2014.

Figure 14. Immunization history questionnaire keying error rates for National Immunization Survey–Teen, 2006–2014
Page 38  Series 1, No. 61

verbatim responses accumulated during 

all previous quarters. The provider data 

file is checked for duplicate records 

and exact duplicates are removed. If 

the IHQ contains a date of birth, sex, 

or name that differs from the household 

interview data, the IHQ is reexamined 

to determine whether it may have been 

filled out for an incorrect child. Provider 

data that appear to have been filled out 

for the wrong child are removed from 

the provider database. When two or 

more providers have reported IHQs for 

a given child or adolescent, decision 

rules are applied to the two reports to 

produce a single, consolidated, most 

complete vaccination history for the 

child, called the "synthesized providerreported vaccination history." The official 

determination of whether the child or 

adolescent is UTD for recommended 

vaccines and vaccine series is based 

on this synthesized provider-reported 

vaccination history.

Matching sheet review (Step 3)—

The matching sheet is a paper form (or 

corresponding electronic image) that 

presents the household and provider data 

for a given child or adolescent in a format 

that is convenient for manual review 

by an editor. Children or adolescents 

with specific discrepancies between the 

household- and provider-reported data 

or between different provider IHQs are 

flagged for such review. The matching 

sheets are examined by an editor who 

determines whether a change in the 

vaccination data is warranted for the 

given child or adolescent. A supervisor 

reviews the results of the manual review. 

The three-step process of a) identifying 

discrepancies, b) flagging a child 

for review, and c) examining results 

manually and correcting is iterative, 

ensuring that a data edit to solve one 

problem does not cause another.

One of the most important elements 

of the matching sheet process is the 

set of editing limits used to evaluate 

vaccination dates. These editing limits 

identify reported vaccination doses that 

are too close to the child’s birthdate 

or too close to each other based on the 

recommended vaccination schedule. 

Table 22 lists the 2014 editing limits for 

NIS–Child and NIS–Teen. 

The editing limits designate which 

cases will be reviewed manually, but they 

do not necessarily specify the changes 

that should be made to the reported data, 

if any. Figure 15 shows the rate of change 

for NIS–Child to reported vaccinations 

due to matching sheet review by year 

from 2005 through 2014. Figure 16

presents the changes to vaccinations for 

NIS–Teen from 2006 through 2014. The 

percentage of children and adolescents 

with one or more changes to reported 

vaccinations varies from year to year 

due to shifts in the composition of the 

sample, variability in provider response 

errors, evolution in the use of different 

combination vaccines, and various other 

factors. Vaccine categories with only 1 

recommended dose, such as measlescontaining and varicella, typically exhibit 

fewer edits during the matching sheet 

process.

Derivation of composite variables 

(Step 4)—A number of composite 

variables are created and included in the 

NIS data files. Composite variables assist 

users and data analysts by eliminating 

duplication of effort, making data easier 

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Child, 2005–2014.

 

Figure 15. Trends in percentage of children with one or more changes to a vaccination among children with one or more valid immunization 

history questionnaires returned, by vaccine category, 2005–2014
Series 1, No. 61  Page 39 

to use, replicating analytic results, and 

increasing the timeliness and accessibility 

of data products. Composite variables 

include dose counts of individual 

vaccinations, indicators of vaccination 

status for individual vaccines and vaccine 

series, age, race and ethnicity of child 

or adolescent, race and ethnicity of the 

child’s or adolescent’s mother, household 

income, and a variety of other childor adolescent- and household-level 

characteristics.

The quality of the derived composite 

variables is assured by a strict reliance 

on specifications, which document 

derivation and format of every composite 

variable that is derived. Tracking 

documents are used to highlight any 

deletions, additions, or modifications to 

the list of derived variables. 

As the data-processing team derives 

the composite variables, an independent 

statistician ensures quality by producing 

a parallel set of composite variables for 

comparison. Frequencies of all derived 

variables are also reviewed and compared 

with distributions from previous years, 

and all composite variables are checked 

for inconsistent or invalid values. If 

any issue is identified, the problem is 

corrected and the parallel test is rerun 

until no further issues are found. As an 

additional measure of quality assurance, 

each variable is checked once more as the 

final data files are produced.

Imputation of missing values 

(Step 5)—NIS uses a single imputation 

method to complete missing values in 

the socioeconomic and demographic 

variables used in the weighting process. 

Missing values of these variables are 

imputed for all children or adolescents 

with a completed household interview, 

using a sequential hot-deck method. 

Table 23 presents the quality assurance 

steps related to imputation of missing 

values.

Missing values are also imputed in 

HIM for the set of children with APD, 

once again using the sequential hot-deck 

method. Use of the reported and imputed 

values enables analysts to use standard, 

complete data methods of statistical 

analysis to study the associations 

between vaccination and health insurance 

variables without results being dependent 

on variable patterns of data missingness.

Final data file production (Step 6)—

After completing all phases of data 

collection and data processing, final data 

products are produced. For NIS, the main 

data product is an annual internal analytic 

data file containing one record for each 

child with a completed household 

interview, and it contains all household 

and provider data for all children and 

adolescents sampled in a given calendar 

year. 

To improve the transparency and 

accessibility of the internal data file, 

it is accompanied by many supporting 

documents, including:

● A detailed data delivery 

memorandum outlining the 

methodology, data collection, 

weighting, and estimation procedure 

for NIS

● A codebook with variable 

information and frequencies for all 

variables on the data file

● SAS programs that researchers can 

use to read in the data file and apply 

formats and labels

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Teen, 2006–2014.

Figure 16. Trends in percentage of adolescents with one or more changes to a vaccination among adolescents with one or more valid 

immunization history questionnaires returned, by vaccine category, 2006–2014
Page 40  Series 1, No. 61

● A report of all editing and corrective 

actions taken

● A record of all call attempts made to 

all sample cases and the outcome and 

disposition code for each call

This information is crucial to making 

NIS data accessible to researchers, so 

they can produce timely and accurate 

analyses of the vaccination statuses of 

children. 

As a final check for consistency and 

accuracy, frequency distributions of all 

variables on the data file are compared 

with the corresponding frequency 

distributions from the prior year. Any 

increase or decrease of more than 5 

percentage points in the proportion of 

respondents answering with a single 

response option, or a net change of more 

than 10 percentage points across all 

response options, is flagged for manual 

review and verification. Vaccination 

coverage rate estimates for all vaccines 

and vaccine series are compared with the 

corresponding rates in prior years. 

The internal data file includes two 

survey weights for use in estimation: 

one weight for the set of children with 

completed household interviews and 

the other weight for the set of children 

with APD. After the weights are derived, 

a quality assurance review process 

brings together a team of statisticians 

who review summary statistics for the 

weights at each step and approve the final 

weights. Once the weights are appended 

to the data file, it is ready for analysis. 

Table 24 shows the quality assurance 

procedures used for the weighting 

process.

Confidentiality and 

Disclosure Avoidance

All information collected in NIS–

Child and NIS–Teen is covered by strict 

assurances of confidentiality and may 

be used only for statistical purposes. For 

discussion of these assurances, refer to 

https://www.cdc.gov/nchs/about/policy/

confidentiality.htm, Section 308(d) of 

the Public Health Service Act, 42 U.S. 

Code 242m(d), the Privacy Act of 1974 

(5 U.S. Code 552a), and for NIS data 

collected through 2014, the Confidential 

Information Protection and Statistical 

Efficiency Act (5 U.S. Code). 

The advance letter, introductory 

script for the CATI interview, and 

request for oral consent each assure 

respondents of the confidentiality of their 

responses and the voluntary nature of 

the survey. Informed consent is obtained 

from the person in the household most 

knowledgeable about the eligible child’s 

immunization history (generally the 

parent or guardian of the child). 

To ensure the privacy of the 

respondents and the confidentiality of 

their information, all CDC staff and 

contractor staff involved with NIS sign 

NCHS’ confidentiality agreement and 

follow instructions to prevent disclosure. 

NIS releases public-use data 

files to allow researchers to conduct 

analyses of U.S. childhood and 

adolescent vaccination data. To prevent 

identification of individual children 

and adolescents and the disclosure of 

information that would result from such 

identification, certain items reported in 

the survey are omitted from the publicuse file.

Prior to release, the proposed 

contents of each public-use file 

undergo extensive review by NCHS’ 

Disclosure Review Board to protect the 

confidentiality of survey participants 

and their data. To ensure confidentiality 

and reduce disclosure risk, several steps 

are taken (92), including removal of 

all household and personal identifiers 

that could be used to match children or 

adolescents to an exogenous file, either 

related or unrelated to NIS; elimination 

of screening, interview, and vaccination 

dates; collapsing, top-coding, or 

bottom-coding select sociodemographic 

variables; and examination of populations 

with rare combinations of demographic 

characteristics, with the possible 

reassignment of such sample cases to 

eliminate the possibility of disclosure. 

These steps ensure that the data can 

be made accessible to researchers 

everywhere while protecting participants’ 

confidentiality. 

Data Dissemination

NIS official estimates 

Estimates of vaccination coverage 

for children aged 19–35 months at the 

national, state, and estimation-area 

levels were routinely released on the 

Web and are available from: https://

www.cdc.gov/vaccines/imz-managers/

coverage/childvaxview/index.html. 

National, state, and estimation-area level 

estimates for adolescents aged 13–17 

are also available online from: https://

www.cdc.gov/vaccines/imz-managers/

coverage/teenvaxview/index.html. Child 

and adolescent vaccination coverage 

information is published periodically in 

CDC’s Morbidity and Mortality Weekly 

Report (MMWR), available from: 

https://www.cdc.gov/vaccines/imzmanagers/coverage/childvaxview/pubspresentations.html and https://www.cdc.

gov/vaccines/imz-managers/coverage/

teenvaxview/pubs-presentations.html.

Public-use data files

NIS–Child and NIS–Teen public-use 

files are available from: https://www.

cdc.gov/vaccines/imz-managers/nis/datatables.html. Each of the annual files is in 

ASCII file format and is accompanied by 

SAS and R input statements for reading 

the ASCII file, a data user’s guide, a 

code book with variable information and 

frequencies, the household interview 

questionnaire, and the provider IHQ.

Evaluation of NIS 

Estimates and Methods

Introduction

Assessing the quality of NIS 

estimates is a critical and ongoing aspect 

of this surveillance program. Existing 

NIS methods were frequently evaluated 

to understand the causes and impacts 

of sampling and nonsampling errors 

on the vaccination coverage estimates, 

and new evidence-based methods were 

implemented wherever possible to 

improve data quality. Four of the major 

projects conducted since 2005 directed 
Series 1, No. 61  Page 41 

at evaluation of the quality of the NIS 

estimates are described. 

● Evaluation of NIS–Child data quality 

using immunization information 

systems (IIS)

● Assessment of representativeness 

of alternative sampling frames for 

NIS–Child

● Comparing NIS–Child vaccination 

coverage rates with those provided 

by the NHIS-PRC 

● Assessment of total survey error 

(TSE)

Evaluation of NIS–Child 

Data Quality Using IIS 

IIS are confidential, populationbased, computerized databases that 

compile information about the doses of 

vaccines children have received from 

participating vaccination providers within 

a defined geographic area (93). Projects 

have been undertaken in collaboration 

with state and local area IIS to evaluate 

the relative completeness of NIS–Child 

and the IIS vaccination histories.

Within a given area, while both NIS–

Child and IIS rely on provider-reported 

vaccination histories, they have different 

objectives. NIS–Child produces estimates 

at the national, state, and limited localarea levels using a standard methodology 

for monitoring vaccination coverage. IIS 

provide vaccination coverage estimates 

for state and local areas, provider 

practices, health plans, schools, and other 

populations. IIS are used by vaccination 

providers, schools, daycares, and other 

authorized organizations to determine 

vaccination UTD status for individuals 

residing in the jurisdiction. IIS include 

functions and features such as clinical 

decision support, reminder or recall 

services, vaccine ordering, and inventory 

management to support immunization 

providers, immunization programs, and 

other stakeholders in guiding public 

health actions related to improving 

vaccination rates and reducing vaccinepreventable disease. 

Matching the provider-reported 

vaccination histories collected in 

NIS–Child and the IIS for a common 

sample of children provides insight 

into the quality of both sources of data. 

Vaccinations included in the IIS but 

not in NIS–Child signal NIS–Child 

incompleteness, while vaccinations 

included in NIS–Child but not in the IIS 

signal IIS incompleteness. 

The first match projects were 

conducted in 2002 and 2004 (94,95). 

Children in the NIS–Child sample for 

whom consent was obtained to contact 

their local IIS were matched to their 

respective IIS database. IIS vaccination 

histories for the matched children were 

then compared with the NIS–Child 

vaccination histories. The quality and 

completeness of the IIS vaccination 

histories were inconsistent and varied 

between different participating IIS. From 

2008 through 2011, 19 additional match 

projects, patterned after the 2002 and 

2004 projects, were conducted again to 

assess the quality and completeness of 

vaccination histories from NIS–Child 

and participating IIS. (No match projects 

were conducted in the 2005–2007 and 

2012–2014 periods.) The 19 IIS were not 

selected as a representative sample of all 

IIS. Participation by an IIS in the match 

studies was by self-selection. The results 

from these studies are not necessarily 

generalizable to all IIS and across all 

years. To preserve the anonymity of the 

participating IIS, summary statistics 

for the set of match projects are 

presented, but the results for the specific 

participating IIS are not identified. 

Table 25 provides information 

from the 19 match projects about the 

completeness of the IIS in terms of 

age-eligible children aged 19–35 months 

within the jurisdiction. (The 19 studies 

represent 15 distinct IIS [some studied 

in multiple years]. State or local area 

immunization program grantees or 

awardees requested that some of their 

Section 317 discretionary funding be 

used for this purpose.) Table 25 shows 

the percentages of NIS–Child children 

who were included in the IIS and 

whether the IIS had complete vaccination 

data for them. Across the 19 IIS, the 

percentage of children not matched to 

the IIS ranged from 0.0% to 31.8%. If 

NIS–Child is taken as the standard, these 

results suggest that some IIS did not 

include all age-eligible children in the 

jurisdiction, and some IIS achieved high 

rates of adequate data for determining the 

vaccination status of those children.

Table 26 presents a comparison 

of NIS–Child, IIS, and synthesized 

vaccination coverage rates among 

children aged 19–35 months from the 

19 studies (96–98). The synthesized 

estimates, denoted by NIS-IIS, reflect a 

combination of NIS–Child and IIS data, 

starting with the NIS–Child data as the 

base and treating the IIS vaccination data 

as an additional provider in determining 

APD and vaccination UTD status. Across 

the 19 IIS, Table 26 shows the minimum 

and maximum differences in vaccination 

coverage rates for the 4+DTaP (4 or 

more doses) vaccine and the 4:3:1:3:3:1 

vaccine series. Compared with NIS–

Child, the synthesized NIS-IIS rates were 

up to 11.9 percentage points higher for 

the 4:3:1:3:3:1 vaccination series and 

were up to 9.0 percentage points higher 

for the 4+DTaP vaccine. Compared with 

IIS, synthesized NIS-IIS rates were up 

to 51.9 percentage points higher for the 

4:3:1:3:3:1 vaccination series and were 

up to 49.3 percentage points higher for 

the 4+DTaP vaccine. The results may 

be taken as evidence of possible underdetermination of UTD status in both the 

NIS–Child data and the IIS data.

Assessment of 

Representativeness of 

Alternative Sampling 

Frames for NIS–Child 

One of the strengths of NIS is 

that it is implemented consistently 

across the United States, allowing 

valid comparisons of estimates across 

time and areas. Despite this strength, 

the NIS–Child methodology has been 

challenged in recent years in two notable 

ways: a) the general environmental 

decline in response rates affecting all 

surveys, including NIS; and b) the 

rising proportion of CPO households. 

These two contextual challenges to 

representativeness raise concern about the 

validity of NIS estimates of vaccination 

coverage. 

To assess the representativeness of 

the traditional landline RDD sampling 

frame, the following evaluations of 
Page 42  Series 1, No. 61

alternative sampling frames were 

sponsored:

● Assessment of cell-phone RDD 

samples in NIS–Child and NIS–

Teen during 2009–2010 prior to 

implementation of a dual-frame 

design in 2011

● Assessment of an address-based 

sampling frame and multimode 

interviewing for NIS–Child in 2009

● Evaluation of the American 

Community Survey (ACS) as a 

sample frame in 2009 to screen 

for households with children aged 

19–35 months and conducting the 

NIS–Child interviews for the eligible 

households

● Evaluation of the use of IIS as 

replacement or supplemental 

sampling frames for children

Assessment of cell-phone RDD 

samples in NIS–Child and NIS–

Teen 

In Q4/2010, a small national cellphone sample was added to NIS–Child 

in preparation for a more complete 

implementation of a dual-frame design 

in 2011. Differences between the official 

2010 NIS–Child estimates (based on the 

single-frame landline RDD design) and 

the 2010 piloted dual-frame estimates 

for specific vaccines and vaccine series 

were assessed and published (99,13). 

Differences in vaccination coverage 

rates for NIS–Child ranged from –1.2 to 

2.2 percentage points, while differences 

for NIS–Teen ranged from –0.6 to 0.6 

percentage points.

Official NIS vaccination coverage 

rates based on the dual-frame sampling 

design were released in 2011. For more 

information about the assessment prior to 

the adoption of the dual-frame design, see 

“Sampling Design, Questionnaire, and 

Response Rates.”

Assessment of an address-based 

sampling frame and multimode 

interviewing

In 2009, researchers evaluated 

the use of the U.S. Postal Service’s 

Delivery Sequence File (DSF) as an 

address-based sampling frame for 

NIS–Child in conjunction with multiple 

modes of household interviewing that 

included telephone, mail, and in-person 

approaches. The DSF is a computerized 

file that contains all delivery point 

addresses serviced by the U.S. Postal 

Service, with the exception of general 

delivery. The DSF provides an essentially 

complete listing of all households in the 

United States, regardless of telephone 

status (100). The ultimate goal of this 

study was to assess both the bias in 

NIS–Child statistics due to NIS–Child’s 

omission of direct interviewing of CPO 

households at that time and the feasibility 

of an address-based sampling (ABS) 

multimode approach for NIS–Child.

The project used a national 

probability sample of addresses, 

including an oversample of addresses in 

Bexar County, Tex. An attempt was made 

to match all sample addresses to landline 

telephone numbers. In the event that a 

telephone number was available, a CATI 

interview was attempted. Otherwise, a 

brief screening form was mailed to the 

sample address, in which a request was 

made of the respondent to mail back a 

telephone number. If the screening form 

was returned, the case was contacted 

via CATI. Nonrespondents in CATI 

and nonrespondents to the screening 

form were mailed a self-administered 

version of the NIS–Child questionnaire, 

according to the Dillman method 

(101). In Bexar County only, in-person 

interviews were attempted if a sampled 

address was determined (via mail or 

telephone) to have age-eligible children 

in the household but had not completed 

the household interview or provided 

consent to contact the child’s vaccination 

provider(s). A total of 520 household 

surveys were completed nationally, 

with 50.8% completed by phone, 44.4% 

completed by mail, and 4.8% completed 

via in-person interviews.

The ABS pilot survey achieved 

a much lower CASRO response rate 

(46.0%) than the 2009 NIS–Child 

(63.7%), and it achieved a similar 

unconditional rate of APD (68.2%) to 

the 2009 NIS–Child (68.7%). Table 27

contains the estimated UTD rates for 

children aged 19–35 months with APD 

for the 2009 NIS–Child and ABS pilot. 

The sample size for the ABS pilot was 

sufficient to detect important differences. 

The vaccination coverage rates are 

generally about two to six percentage 

points higher in the 2009 NIS–Child. The 

only statistically significant difference 

between the vaccination coverage rates is 

for the 4:3:1:3:3:1:3 vaccine series.

Several aspects of the ABS 

multimode approach piloted in 2009 

would be challenging for NIS–Child. 

There are sensitive but critical items on 

the NIS–Child questionnaire that were 

skipped more often in the paper-andpencil-interview (PAPI) mode than in 

the CATI mode of the ABS pilot. PAPI 

item nonresponse rates were 0.7%, 

2.9%, and 7.0% for child’s sex, child’s 

race, and respondent’s relationship 

to child, respectively, compared with 

the CATI item nonresponse rates of 

0% for the same items. For the CATI 

mode, interviewers had the opportunity 

to address respondents’ questions and 

concerns in real time, resulting in no item 

nonresponse to these and other critical 

items. While not tested in this pilot, the 

addition of other surveys in the NIS 

family, such as NIS–Teen or NIS–Flu, 

to the overall interview, would increase 

the overall length and complexity of the 

PAPI household questionnaire, which 

in turn would likely reduce participants’ 

willingness to respond. The study also 

established that the 2009 ABS pilot 

design would not be cost effective 

for NIS–Child, in part because of the 

substantial amount of screening that must 

be conducted to find households with 

age-eligible children. 

Based on the limitations and the 

potential increase in costs identified 

in the 2009 ABS pilot and the general 

comparability of vaccination coverage 

rates between the ABS pilot and the 

2009 NIS–Child, the telephone survey 

design for the household data-collection 

phase of NIS–Child was continued, and 

the coverage of CPO households was 

addressed by adding a cell-phone RDD 

sample (to the existing landline RDD 

sample) in a dual-frame approach. 
Series 1, No. 61  Page 43 

Evaluation of NIS–Child using 

ACS

A pilot study was conducted in 2009 

to evaluate the use of ACS as a sampling 

frame for NIS–Child. Conducted by 

the U.S. Census Bureau, ACS is a large 

ongoing survey that provides data about 

residents of the United States every year 

at national, state, and local levels. ACS 

is selected from a sampling frame that 

provides essentially complete coverage 

of all households in America, regardless 

of telephone status. The regular ACS 

interviews collect enough information to 

determine households that contain NISeligible children and adolescents. The 

2009 NIS-ACS pilot study was conducted 

as a follow-on survey to ACS, through 

which a sample of ACS respondents 

identified to be in NIS–Child age-eligible 

households were asked to provide 

consent to participate in the NIS–Child 

household survey after completing the 

ACS survey.

The 2009 NIS-ACS pilot study was 

conducted in Florida, using a stratified 

random sampling design with three strata: 

Duval County, Dade County, and the rest 

of Florida. The Census Bureau selected a 

subsample of ACS respondents to achieve 

approximately 310 children with APD 

within each of these three areas, and 

Census Bureau interviewers conducted 

the in-person or telephone household 

interviews between August and October 

of 2009. The sample size for the pilot 

study was determined to ensure that 

meaningful differences in vaccination 

coverage rate estimates between the 2009 

NIS-ACS and the 2009 NIS–Child could 

be statistically detected. The first mailing 

of IHQs occurred in October 2009 on 

behalf of the sampled children for whom 

permission to contact providers was 

obtained, and the closing of the provider 

portion of the pilot study occurred in June 

2010. 

Vaccination coverage was estimated 

for each of the nine recommended 

childhood vaccines, and the estimates 

from the 2009 NIS-ACS pilot were 

compared with estimates from the 

2009 NIS–Child, as shown in Table 28. 

Vaccination coverage was statistically 

significantly higher in the NIS–Child 

sample for 1 or more varicella doses after 

age 12 months and for seasonal influenza.

For the 2009 ACS-NIS pilot study 

and the 2009 NIS–Child in Florida: 

● The percentages of completed 

telephone interviews among 

households with age-eligible children 

were 77.7% and 81.6%, respectively

● The percentages of households 

giving permission to contact 

vaccination providers, among 

completed interviews, were 93.2% 

and 80.2%, respectively

● The percentages of sampled children 

with APD, among those with a 

completed interview and permission 

to contact vaccination providers, 

were 89.8% and 84.0%, respectively

The pilot study demonstrated 

that ACS could provide estimates of 

vaccination coverage comparable with 

estimates based on the NIS–Child 

telephone sampling frame, however, the 

ACS sampling frame did not provide 

sufficient numbers of children aged 

19–35 months within each NIS–Child 

estimation area to achieve the NIS–

Child precision requirement (i.e., 7.5% 

coefficient of variation for the estimator 

of the vaccination coverage rate when the 

true but unknown rate is 50% without use 

of an additional sampling frame). Another 

issue included the possibility that the 

ACS frame would not be available for 

NIS–Child, NIS–Teen, and NIS–Flu each 

data-collection year without interruption.

Based on the cited limitations in 

the size of the sample to deliver the 

necessary precision and the lack of 

guaranteed access to the ACS sample 

frame, NIS data collection using the dualframe landline RDD and cell-phone RDD 

telephone survey design was continued.

Evaluation of the use of IIS as 

replacement or supplemental 

sampling frame

The 2008 NIS-IIS sampling 

frame evaluation was conducted in 

collaboration with two state IIS (to 

preserve anonymity, referred to as States 

A and B) to evaluate if the IIS list of 

children could replace or supplement 

the NIS–Child standard landline RDD 

sampling frame. The evaluation differed 

from the NIS-IIS match projects 

described earlier. In the sampling frame 

study, an independent list sample of 

children’s records was selected from 

each of the two participating IIS, and the 

list sample cases were fielded using the 

NIS–Child CATI household survey with 

the child’s parent or guardian. Assuming 

parental consent was given during the 

household phone interview, the provider 

record check was conducted for the IIS 

sample of age-eligible children aged 

19–35 months to obtain provider data just 

as in NIS–Child. 

The IIS list sample for States A and B 

resulted in different proportions of 

nonlocatable cases (i.e., cases for which 

the state locating process did not yield a 

current address or telephone number): 

29% and 14%, respectively. In addition, 

there were a substantial number of cases 

that were coded in the telephone center as 

nonworking or out-of-scope (16% in 

State A, 26% in State B), or as ineligible 

households (20% in State A, 18% in 

State B). 

The yield rates (completed cases 

divided by the number of sample cases 

released and located for data collection) 

were similar for the two states, 15% and 

19% for States A and B, respectively. 

Provider consent was greater than 80% 

for each state and APD were obtained for 

approximately 90% of the sample cases 

for which provider consent was obtained.

Table 29 presents differences in 

estimated vaccination coverage rates 

between the IIS and NIS–Child samples 

for the period Q1/2008–Q2/2008, based 

on provider-reported data. For State A, 

vaccination rates for the NIS–Child and 

IIS samples were within four percentage 

points of one another and differences 

were not significant. For State B, the 

vaccination rates were within three 

percentage points and differences were 

not significant.

Results from the 2008 NIS-IIS 

sampling frame evaluation suggest that 

the use of IIS as a replacement for the 

landline RDD telephone sampling frame, 

or the use of IIS in conjunction with the 

landline RDD frame in a multiframe 

sampling design, could be potentially 

feasible approaches for NIS–Child 

in the future. Major limitations of 
Page 44  Series 1, No. 61

the IIS frames include the substantial 

state-to-state variation in population 

coverage of young children and the 

limited availability of accurate contact 

information in IIS records, such as 

address and phone number (102). The 

population coverage, availability of 

accurate contact information, and the 

overall operational feasibility of using 

IIS as a supplemental sampling frame for 

NIS–Child continue to be explored using 

additional state IIS (97,98,103,104).

Comparing NIS–Child 

Vaccination Coverage Rates 

With Those Provided by 

NHIS-PRC

Reliance on household reports of 

childhood immunizations is subject to 

recall errors (105). To determine the 

accuracy of the household responses 

in NHIS, the National Immunization 

Provider Record Check Study (NIPRCS) 

was implemented starting in 1994. Its 

purpose was to evaluate the accuracy 

of household reports of children’s 

immunization histories by comparing 

the household reports with the reports 

from the children's immunization 

providers, and to produce national 

estimates of vaccination coverage using 

both the household and provider reports. 

Documentation and data from the 

1997–1999 NIPRCS are available from: 

https://www.cdc.gov/nchs/nhis/niprcs.

htm.

Building on the work completed in 

NHIS-NIPRCS, during 2009 through 

Q3/2013, evaluations were conducted to 

compare the vaccination coverage rates 

of children enumerated in NHIS with 

the rates in NIS–Child (106). NHIS was 

based upon an area-probability sampling 

frame, which had essentially complete 

coverage of all households regardless 

of telephone status, and was conducted 

using face-to-face interviews. A provider 

record check (PRC) was conducted for 

children aged 19–35 months identified in 

the household interviews, using NIS-like 

methods and referred to as the NHISPRC. The NHIS-PRC reported here was 

conducted from 2009 through Q3/2013. 

Taking NHIS-PRC as the standard, 

the comparison offers evidence about 

the validity of NIS–Child vaccination 

coverage estimates. Because of its 

relatively small sample size, however, 

the NHIS-PRC estimates were prepared 

and used for comparison purposes at the 

national level and not at the state or localarea levels. 

Table 30 presents response rates 

for NIS–Child and NHIS for the period 

2009–2013. NHIS sample child response 

rates and NIS–Child household-phase 

response rates are conceptually similar, 

although the NHIS rates refer to children 

under age 18 years while NIS–Child rates 

refer to children aged 19–35 months. 

NHIS sample child response rates were 

around 10 percentage points higher than 

the NIS–Child household-phase response 

rates for the landline sample and more 

than twice as high as NIS–Child for the 

cell-phone sample. 

Both single-frame landline RDD 

sample and dual-frame landline and 

cell-phone RDD sample estimates 

derived from NIS–Child were compared 

with NHIS-PRC estimates. Vaccination 

coverage estimates for NIS–Child derived 

from the single-frame landline RDD 

sample and the NHIS-PRC for the 2-year 

period Q1/2009–Q4/2010 are presented 

in Table 31. NIS–Child single-frame 

landline estimates were one to three 

percentage points higher than NHIS-PRC 

estimates for three of seven individual 

vaccines and almost three percentage 

points greater for the 4:3:1:3:3:1:3 series. 

Table 32 compares NIS–Child 

dual-frame landline and cell-phone 

sample vaccination coverage estimates 

with NHIS-PRC estimates for the 1-year 

period 2010. (The NIS–Child estimates 

combined the Q4/2010 national cellphone RDD pilot sample with the 

standard Q1/2010–Q4/2010 landline 

RDD sample.) Differences were small 

and none of the differences were found 

to be statistically significant. The 

comparisons were generally consistent 

with the conclusion that the NIS–Child 

dual-frame estimators were not subject 

to differential bias compared with the 

NHIS-PRC estimators.

Assessment of TSE

Introduction

TSE is the sum of the errors that 

arise at every step of a survey, including 

both sampling and nonsampling errors, 

such as coverage, nonresponse, and 

measurement errors (107). In the 

assessment of TSE for NIS, the survey’s 

total error is treated as a random variable 

with a statistical distribution conditional 

on the observed NIS. Analysis for the 

2009–2012 NIS–Child and NIS–Teen 

was conducted to estimate the TSE 

distributions for estimated vaccination 

coverage rates for each data-collection 

year and to monitor any year-to-year 

changes in total error. As mentioned 

previously, the 2009–2010 surveys were 

based on the single-frame landline RDD 

design, while the 2011–2012 surveys 

were based on the dual-frame landline 

and cell-phone RDD design (108,109). 

The TSE methods are described briefly 

below, followed by a synopsis of the 

results of the TSE analysis for 2009–2012.

Methods

The TSE model framework may 

be summarized as follows: 1) specify a 

distribution function for each component 

of sampling and nonsampling error in 

the survey process, 2) derive estimates 

of the parameters of the component 

distributions from the best sources or 

analyses available, and 3) apply a Monte 

Carlo simulation approach to combine 

the components of error into a total error 

distribution for each vaccination coverage 

rate estimate examined (110,111). 

The mean of the TSE distribution is 

used as a summary measure of the total 

error in the vaccination coverage rate 

estimates. From a frequentist perspective, 

means found to be substantially different 

from zero signal the possibility of 

bias in the NIS estimators. The TSE 

models summarized in this report 

include two types of nonsampling error: 

incompleteness of the sampling frame 

and nonresponse.
Series 1, No. 61  Page 45 

Results

Figure 17 displays the means of the 

TSE distributions for selected NIS–Child 

final weighted estimates for calendar 

years 2009 through 2012. The mean 

TSE estimates for all three vaccination 

coverage rates in 2010–2012 were 

around –2 to 2 percentage points, and 

0 percentage points fell within the 95% 

credible interval for total error. 

Figure 18 similarly displays the 

means of the TSE distributions for 

selected NIS–Teen vaccination coverage 

rate estimates. For 1 or more doses of 

Tdap and 1 or more doses of MenACWY, 

the mean error was smaller in 2011 and 

2012 than in 2009 and 2010, but this 

finding did not appear to hold for 1 or 

more doses of HPV. The means of TSE 

distributions tended to be different from 

zero (i.e., the 95% credible interval fails 

to cover zero percentage points).

Conclusions

NIS–Child estimators appeared 

to lack bias in 2010–2012, but they 

appeared to be upward biased in 2009 

relative to the available benchmarks used 

in the TSE analysis. NIS–Teen estimators 

appeared to benefit from the dual-frame 

landline and cell-phone RDD design, but 

they were biased by several percentage 

points in 2011 and 2012. The TSE 

analyses reported here were themselves 

subject to a multitude of sampling 

and nonsampling errors arising in the 

evaluation studies that form the basis for 

the analyses. 

Recent TSE analysis of the 2012 

NIS expanded in scope to include not 

only error due to incompleteness of 

the sampling frame and error due to 

nonresponse, but also classification 

error due to provider underreporting of 

vaccination status, using data from the 

NIS-IIS match studies described earlier 

(111).

Other Surveys in the 

NIS Family of Surveys

Introduction

Other surveys in the NIS family of 

surveys include NIS–Adult conducted 

in 2007, the National 2009 H1N1 Flu 

Survey (NHFS) conducted during the 

2009–2010 influenza season, NIS–

Kindergarten (NIS–K) conducted 

in 2013, and the ongoing NIS–Flu 

conducted every influenza season 

beginning with the 2010–2011 season.

NIS–Adult, 2007

The 2007 NIS–Adult was 

conducted to provide information 

related to vaccination coverage among 

adults aged 18 and over for vaccines 

recommended by the Advisory 

Committee on Immunization Practices, 

Figure 17. Mean total survey error for the 4:3:1:3:3:1 vaccination series and 1 or more MMR and 4 or more DTaP vaccines, by survey year, 

2009–2012

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Child, 2009–2012. 
Page 46  Series 1, No. 61

including influenza, pneumococcal, 

tetanus-diphtheria, tetanus-diphtheriaacellular pertussis, hepatitis A, hepatitis 

B, and HPV vaccines. It built upon 

previous surveys, including, the Elderly 

Immunization Survey (conducted 

in 2003) and the National Adult 

Immunization Survey (conducted in 

2004), which were limited to adults 

aged 65 and over and aged 50 and over, 

respectively (112,113). Target sample 

sizes for NIS–Adult were determined for 

nine race or ethnicity domains (Hispanic, 

non-Hispanic black, and other) by age 

group (18–49, 50–64, and 65 and over), 

with oversampling in the Hispanic and 

non-Hispanic black domains.

NIS–Adult data were collected 

using a landline telephone survey from 

May 3, 2007, through September 2, 

2007. The survey utilized two distinct 

sampling frames: 1) household telephone 

numbers collected from NHIS-completed 

interviews from 2005 (except for the 

third quarter, July–September) and 2006 

(only the first quarter, January–March), 

and 2) an age-targeted list sample of 

household telephone numbers obtained 

from a vendor. All telephone numbers 

from the NHIS sample with nonmissing 

age and race or ethnicity information 

were included in the survey. The agetargeted sample supplemented the NHIS 

sample because the NHIS sample was not 

large enough to obtain the study target 

number of completed interviews. 

One adult was selected for the survey 

per household and 7,055 interviews 

were completed. Key indicators appear 

in Table 33; 2,899 interviews were 

completed in the NHIS sample, 4,156 

in the age-targeted sample, and 7,055 

overall. Conditional on NHIS itself, 

the CASRO response rate in the NHIS 

sample was 33.5%, the response rate 

in the age-targeted sample was 29.4%, 

and the combined response rate over 

both samples was 30.5%. The relatively 

low response rate in the NHIS sample 

was the result of two factors: the time 

lag between the NHIS and NIS–Adult 

interviews and the oversampling of the 

race or ethnicity domains.

Estimates from NIS–Adult have been 

published (114–119). 

NHFS, 2009

The large screening samples 

used for NIS–Child provide a unique 

capability for responding to public health 

emergencies, such as the influenza 

A(H1N1)pdm09 pandemic from 2009 

through 2010. The response to this 

emergency necessitated the generation 

of timely, valid estimates of influenza 

vaccination coverage with both the 

pandemic and seasonal influenza 

vaccines. For this reason, NHFS was 

developed, building upon the preexisting 

framework of NIS–Child. A standalone 

survey for adults and children was 

developed, and the resulting survey 

data were augmented by data from the 

preexisting NIS–Child, NIS–Teen, and 

National Survey of Children with Special 

Health Care Needs. Consequently, NHFS 

combined data from a new survey of 

 

SOURCES: National Center for Immunization and Respiratory Diseases and NCHS, National Immunization Survey–Teen, 2009–2012. 

Figure 18. Mean total survey error for 1 or more Tdap and 1 or more meningococcal vaccines, and 1 or more HPV vaccines for females, by 

survey year, 2009–2012
Series 1, No. 61  Page 47 

adults and children and from the usual 

NIS–Child and NIS–Teen (to which 

additional questions had been added). 

NHFS interviews were conducted from 

October 2009 through June 2010.

NHFS was designed to provide 

a) separate estimates of vaccination 

coverage rates for adults (18 and over) 

and children (6 months–17 years); 

b) national estimates of vaccination 

coverage rates and other statistics for the 

total population of adults and children, 

and by race and ethnicity, and for various 

priority domains on a weekly basis, in 

which the survey week was defined by 

the Saturday week-ending date; c) weekly 

estimates within 4 to 6 days following 

the end of the survey week; d) estimates 

of vaccination coverage rates and other 

statistics at the state level on a monthly 

basis; and e) estimates with the best 

possible survey response and the least 

possible nonresponse bias, within cost 

and timeliness constraints. 

To achieve these objectives, a new 

rotation sampling design was developed. 

The standalone survey component used 

a dual-frame sampling design consisting 

of landline RDD and cell-phone RDD 

samples contacted to identify residential 

households. Within each household in 

the landline portion of the NHFS sample, 

one adult and one child (if present in the 

respondent’s household) were randomly 

selected as the subject(s) of the survey. 

For each active personal cell-phone 

number (APCN) reached, the contacted 

adult was selected, while one child (if 

present in the respondent’s household) 

was selected at random. For both landline 

and cell-phone samples, selected adults 

were interviewed about themselves, and 

a resident parent or guardian of the child, 

who was in most cases also the selected 

adult, was interviewed about the child. 

The standalone survey component 

of NHFS used rolling weekly samples. 

A new sample was released weekly, 

with each sample undergoing active data 

collection for 5 weeks. Each sampled 

telephone number was called repeatedly 

during the 5-week period, until the 

number was resolved as nonresidential, 

confirmed as a refusal, or classified 

as a completed interview. Completed 

interviews obtained within a survey week 

were used in generating the estimates for 

that survey week. Estimates for a survey 

month were based upon all completed 

interviews from survey weeks within the 

survey month.

The rotation design created for the 

NHFS sample, especially the use of the 

responses from five different weekly 

samples in the estimation for the current 

week, is unique. In traditional survey 

research, a single sample would be used 

to make estimates for a given time period. 

This approach for the NHFS would 

have meant that the survey would only 

use interviews achieved in the current 

week from members of the current week 

sample and would not benefit from the 

callback efforts possible with a more 

extended data-collection period. In 

planning this survey design, a model of 

the response mechanism in which the 

probability of response varies with the 

number of weeks since sample release 

was developed. The survey objectives 

and the response model drove the 

decision to use the rotating panel design. 

Given the unique survey design 

of NHFS, a statistically appropriate 

method of weighting was developed and 

subsequently implemented. The data 

were weighted to adjust for nonresponse 

and for households that do not have a 

telephone; to account for overlap in the 

rotating panel design; and to match the 

age, sex, and race-ethnicity distribution 

of the population of children by state on a 

monthly basis.

Key indicators for NHFS, cumulative 

over all of the rolling weekly samples, 

as of the end of the influenza season are 

shown in Table 34. Completed interviews 

were achieved for 45,750 households in 

the landline sample, 11,080 households 

in the cell-phone sample, and 56,830 

households in the combined sample. 

The CASRO response rates were 33.8%, 

26.2%, and 32.0% in the landline, 

cell-phone, and combined samples, 

respectively.

The official release of estimates of 

pH1N1 influenza vaccination coverage 

in the 2009–2010 season have been 

published (120) and are available on 

CDC’s FluVaxView website at:

https://www.cdc.gov/flu/fluvaxview. 

Papers featuring NHFS data have been 

written (120–124). More information 

about NHFS, including a public-use file 

and data user’s guide, is available from: 

https://www.cdc.gov/nchs/nis/data_files_

h1n1.htm. 

NIS–Kindergarten, 2013

NIS–K was fielded in Q4/2013 

using the NIS–Child sample to test the 

collection of school-related information 

from parents of children of kindergarten 

age (5–7 years) for whom vaccinations 

had been exempted and the reasons 

for exemption. The NIS–K household 

interview followed administration of 

the NIS–Child, NIS–Teen, and NIS–Flu 

screenings and interviews. Households 

with children aged 5–7 years were 

eligible to complete the NIS–K interview, 

and the survey made use of the household 

rosters collected in the existing NIS–

Teen and NIS–Flu screeners to identify 

households with children aged 5–7. One 

age-eligible child was randomly selected 

to be the focus of NIS–K. A parental 

concerns module was also included in 

the survey to collect information about 

the respondent’s perceptions of vaccines, 

concerns the respondent had when the 

child was vaccinated, influences on the 

decision to vaccinate, and delay and 

refusal to vaccinate. A PRC collected 

provider-reported vaccination histories 

for children with parental consent to 

contact vaccination providers.

Key indicators for NIS–K appear 

in Table 35. The survey included 2,348 

completed interviews: 580 from the 

landline frame and 1,768 from the 

cell-phone frame. The overall CASRO 

response rates were 50.8% in the landline 

sample and 25.7% in the cell-phone 

sample. In the landline sample, 74.5% 

of respondents consented to participate 

in the PRC, and 70.6% gave consent 

from the cell-phone sample. The landline 

sample APD rate was 66.0% of children 

with completed interviews, and the cellphone sample APD rate was 61.4% of 

children with completed interviews.

NIS–K was a pilot study with a 

limited sample size. Data have been used 

to estimate the percentage of children 

with exemptions, the risk of undervaccination attributable to exemptions, 
Page 48  Series 1, No. 61

and the percentage of children whose 

parents were notified by schools that 

their child did not have all vaccinations 

required for kindergarten entry. 

Additional information about NIS–K is 

available (125).

NIS–Flu, 2010–2014 

NIS–Flu is a national dual-frame 

(landline and cell phone) RDD survey 

of households with children aged 6 

months–17 years. NIS–Flu includes three 

components: NIS–Child for children aged 

19–35 months, NIS–Teen for adolescents 

aged 13–17, and the NIS–Child Influenza 

Module (NIS–CIM) for children aged 

6–18 months and 3–12 years who are 

identified during screening interviews 

for NIS–Child and NIS–Teen. NIS–Flu 

was started in October 2010 to assess 

annual influenza vaccination coverage 

at the national, state, and selected local 

levels, including selected U.S. territories. 

Parents and guardians are asked if their 

children had an influenza vaccination, 

and if so, how many vaccine doses the 

child had received. For each reported 

dose, the month and year administered 

and the type of vaccination (injection 

or nasal spray) are recorded. Additional 

questions regarding the type of place 

vaccinations were received, as well 

as intent to vaccinate by the end of 

the influenza season among those not 

yet vaccinated, were asked. In recent 

influenza seasons, additional questions 

have been added to the questionnaires 

related to doctor or other health care 

professional recommendations for 

influenza vaccination, as well as parental 

preference regarding vaccine delivery 

method by injection or nasal spray.

NIS–Flu estimates are based on the 

parent- or guardian-reported data, not 

on provider-reported data. Influenza 

vaccination coverage estimates are 

calculated throughout the influenza 

season using Kaplan-Meier survival 

analysis to determine the cumulative 

influenza vaccination coverage (1 or 

more doses) during the July–May season 

using monthly interview data collected 

from October through June (126).

Table 36 displays the end-ofinfluenza-season cumulative key 

indicators for NIS–CIM. (Key indicators 

for the other components of NIS–Flu 

were discussed earlier in this report for 

NIS–Child and NIS–Teen.) For example, 

at the close of the 2013–2014 season, 

completed interviews had been obtained 

for 35,393 households in the landline 

sample, 44,413 in the cell-phone sample, 

and 79,805 in the combined sample, with 

CASRO response rates of 58.6%, 32.0%, 

and 40.1% in the landline, cell-phone, 

and combined samples, respectively.

For additional information on 

influenza vaccination coverage estimates 

from NIS–Flu, visit the FluVaxView 

website at: https://www.cdc.gov/flu/

fluvaxview/. More information can be 

found in papers featuring NIS–Flu data 

(127,128).

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Page 54  Series 1, No. 61

Table 1. Vaccines monitored by National Immunization Survey–Child in 2014

Vaccine recommended for routine administration1 Recommended dose1

Diphtheria and tetanus toxoids and acellular 

pertussis vaccine (DTaP) 4 doses

Poliovirus vaccine (Polio) 3 doses

Measles, mumps, and rubella vaccine (MMR) 1 dose

Haemophilus influenzae type b vaccine (Hib) 3 or 4 doses depending on the manufacturer of 

the vaccine

Hepatitis B vaccine (HepB) 3 doses

Varicella zoster vaccine (Var) 1 dose

Pneumococcal conjugate vaccine (PCV) 4 doses (infants and children who have 

received 1 or more doses of PCV7 should 

complete the immunization series with 

PCV13. A single supplemental dose of PCV13 

is recommended for all children aged 14–59 

months who have received 4 doses of PCV7 

or another age-appropriate, complete PCV7 

schedule.)

Hepatitis A vaccine (HepA) 2 doses

Rotavirus vaccine (RV) 2 or 3 doses depending on the manufacturer of 

the vaccine

Influenza vaccine (Flu) 1 or 2 doses annually

1

See the 2014 recommended vaccination schedule at: https://www.cdc.gov/vaccines/schedules/downloads/past/2014-child.pdf.

Table 2. Vaccines monitored by National Immunization Survey–Teen in 2014

Recommended vaccine1 Recommended dose1

Tetanus-diphtheria-acellular-pertussis vaccine (Tdap) 1 dose

Meningococcal vaccine (MenACWY) 1 dose

Human papillomavirus vaccine (HPV) 3 doses

Measles, mumps, and rubella vaccine (MMR) 2 doses

Hepatitis B vaccine (HepB) 3 doses

Varicella zoster vaccine (Var) 2 doses

Hepatitis A vaccine (HepA) 2 doses

Pneumococcal polysaccharide vaccine (PPSV23) Not routinely recommended for adolescents 

aged 13–17; recommended for adolescents 

with certain health or lifestyle conditions that 

put them at an increased risk for serious 

diseases. See Table 1 for recommended 

doses for younger children.

Influenza vaccine (Flu) 1 dose annually

1

See the 2014 recommended vaccination schedule at https://www.cdc.gov/vaccines/schedules/downloads/past/2014-child.pdf.
Series 1, No. 61  Page 55 

Table 3. Major changes since 2005 in the protocol of National Immunization Survey–Child 

random-digit-dialing sample 

Year or quarter/year Description

2006 Began offering a token of appreciation to cases that had refused at any point 

in the interview after reporting there was a child under age 4 years in the 

household

2007 Introduced hybrid-dialing of landline telephone numbers, allowing cases to be 

called by predictive dialers until contact is established, and by preview dialers 

afterward

2007 Reduced the number of estimation areas from the original 78 immunization 

action plan areas to 56 core estimation areas, plus a varying number of rotating 

areas updated annually

2007 Eliminated the differentiation between “soft” and “hard” refusals 

2008 Added a callback to minor-only households to confirm status

2008 Stopped coding “likely” households based on answering machine messages 

2009 Stopped listening to entire answering machine messages, if not leaving a 

message

Q4/2010 Introduced an experimental national cell-phone sample as a complement to the 

landline sample, in which screening was conducted for cell-phone-only or cellphone-mainly status

Q1/2011 Modified the sampling design to include a cell-phone sample stratified by 

estimation area

Q2/2011 Changed the determination of age eligibility from the date of birth falling in range 

on the date of screening to the date of birth falling in range at any point during 

the calendar quarter

Q2/2011 Removed screening for cell-phone-only or cell-phone-mainly status and instead 

interviewed all cell-phone respondents (a take-all design)

Q1/2012 Increased the size of the cell-phone sample; allocated sample size to the two 

random-digit-dialing sampling frames to minimize the cost of data collection, 

subject to a constraint on the coefficient of variation of the estimated vaccination 

coverage rate

Q1/2012 Removed Section A from household interview; as a result, could not use 

household shot-card data to determine adequate provider data status. Revised 

adequate provider data definition so children with at least one reported 

vaccination on a returned immunization history questionnaire were considered 

to have adequate provider data

Q1/2013 The dual-frame sample allocation was based on a projection of the most 

recent estimates of the population distribution forward to 2013. This method of 

projecting population estimates by telephone status forward resulted in a larger 

allocation to the cell-phone sample 

Q2/2013 The household questionnaire was modified to accommodate the inclusion of 

Guam data collection in quarter 2 only

Q1/2014 An optimal allocation between sampling frames was not possible due to budget 

constraints, resulting in a smaller allocation to the cell-phone sample 

Q1/2014 A prescreening process was introduced for the cell-phone sample to remove a 

portion of the nonworking cell-phone numbers prior to dialing. Ten percent of 

the cell-phone sample was designated as “holdout” sample, where numbers 

were dialed even if the prescreening process indicated they were nonworking. 

This holdout sample allows for continual monitoring of the effectiveness of the 

prescreening

Q1/2014 Prior to the first quarter of 2014, landline-sample telephone numbers that 

were ported to cell phones were not dialed and were treated as out of scope. 

Beginning with the first quarter of 2014, landline sample numbers identified as 

ported cell phones prior to being loaded for dialing are not finalized as out of 

scope but are instead dialed using the cell-phone dialing protocol. Numbers not 

identified as ported cell phones before being loaded for dialing but subsequently 

identified as ported cell phones continue to be finalized as out of scope

Q3/2014 The household questionnaire was modified to accommodate the inclusion of 

Puerto Rico data collection. A new Spanish-language immunization history 

questionnaire was used for Puerto Rico
Page 56  Series 1, No. 61

Table 4. Population of children aged 19–35 months on July 1, 2013, for the 56 core estimation areas in National Immunization Survey–Child, 

by telephone status

Area name

Area 

number

Total 

children

19–35

months

Landline-only

households

Landline and cell-phone 

households

Cell-phone-only 

households

Phoneless

households

Proportion

Children

19–35 

months Proportion

Children 

19–35 

months Proportion

Children

19–35 

months Proportion

Children

19–35 

months

Total in the United States

(excluding U.S. territories) . . . . . . . . . . . ... 5,724,088 0.030 171,453 0.368 2,107,610 0.576 3,297,995 0.026 147,030

HHS Region 1

Connecticut . . . . . . . . . . . . . . . . . . . . . . . 1 56,042 0.061 3,415 0.531 29,763 0.394 22,107 0.014 757

Massachusetts . . . . . . . . . . . . . . . . . . . . . 2 104,130 0.038 3,988 0.543 56,572 0.403 41,972 0.015 1,598

Maine . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 18,068 0.022 406 0.353 6,384 0.608 10,983 0.016 295

New Hampshire . . . . . . . . . . . . . . . . . . . . 5 19,233 0.007 140 0.504 9,694 0.475 9,130 0.014 269

Rhode Island . . . . . . . . . . . . . . . . . . . . . . 6 15,766 0.033 520 0.481 7,591 0.460 7,250 0.026 405

Vermont . . . . . . . . . . . . . . . . . . . . . . . . . . 7 8,294 0.051 422 0.563 4,666 0.385 3,190 0.002 16

HHS Region 2

New Jersey . . . . . . . . . . . . . . . . . . . . . . . 8 157,366 0.030 4,709 0.597 93,919 0.353 55,477 0.021 3,261

New York—rest of state . . . . . . . . . . . . . . 10 170,589 0.051 8,699 0.519 88,609 0.406 69,245 0.024 4,036

New York—City of New York . . . . . . . . . . 11 170,839 0.057 9,801 0.507 86,664 0.407 69,515 0.028 4,859

HHS Region 3

District of Columbia . . . . . . . . . . . . . . . . . 12 11,696 0.010 117 0.542 6,344 0.428 5,007 0.019 228

Delaware . . . . . . . . . . . . . . . . . . . . . . . . . 13 16,545 0.004 66 0.576 9,537 0.406 6,710 0.014 232

Maryland . . . . . . . . . . . . . . . . . . . . . . . . . 14 106,838 0.012 1,231 0.526 56,240 0.434 46,417 0.028 2,950

Pennsylvania—rest of state . . . . . . . . . . . 16 174,120 0.019 3,240 0.505 87,993 0.447 77,757 0.029 5,130

Pennsylvania—Philadelphia County . . . . 17 34,576 0.028 981 0.352 12,166 0.592 20,452 0.028 977

Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 150,476 0.030 4,570 0.471 70,941 0.475 71,540 0.023 3,425

West Virginia . . . . . . . . . . . . . . . . . . . . . . 19 28,465 0.047 1,337 0.319 9,085 0.594 16,913 0.040 1,130

HHS Region 4

Alabama . . . . . . . . . . . . . . . . . . . . . . . . . 20 84,627 0.034 2,905 0.301 25,484 0.638 54,030 0.026 2,208

Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 310,138 0.026 8,172 0.327 101,368 0.611 189,364 0.036 11,234

Georgia . . . . . . . . . . . . . . . . . . . . . . . . . . 25 191,743 0.016 3,129 0.335 64,322 0.616 118,106 0.032 6,186

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . 27 77,267 0.030 2,301 0.264 20,424 0.670 51,776 0.036 2,766

Mississippi . . . . . . . . . . . . . . . . . . . . . . . . 28 57,195 0.018 1,004 0.210 12,007 0.746 42,663 0.027 1,521

North Carolina . . . . . . . . . . . . . . . . . . . . . 29 177,250 0.040 7,042 0.325 57,548 0.611 108,383 0.024 4,277

South Carolina . . . . . . . . . . . . . . . . . . . . . 30 82,621 0.018 1,476 0.294 24,251 0.660 54,570 0.028 2,324

Tennessee . . . . . . . . . . . . . . . . . . . . . . . . 31 115,714 0.028 3,275 0.293 33,848 0.649 75,121 0.030 3,470

HHS Region 5

Illinois—rest of state . . . . . . . . . . . . . . . . 34 170,421 0.008 1,445 0.376 63,998 0.594 101,315 0.021 3,663

Illinois—City of Chicago. . . . . . . . . . . . . . 35 59,237 0.009 505 0.360 21,327 0.606 35,904 0.025 1,501

Indiana . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 120,179 0.041 4,907 0.328 39,370 0.591 71,064 0.040 4,838

Michigan . . . . . . . . . . . . . . . . . . . . . . . . . 38 162,941 0.028 4,562 0.295 48,112 0.648 105,652 0.028 4,615

Minnesota . . . . . . . . . . . . . . . . . . . . . . . . 40 100,427 0.014 1,398 0.416 41,821 0.555 55,754 0.014 1,454

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 195,908 0.018 3,489 0.311 61,006 0.629 123,182 0.042 8,231

Wisconsin . . . . . . . . . . . . . . . . . . . . . . . . 44 98,363 0.027 2,679 0.333 32,721 0.614 60,395 0.026 2,568

HHS Region 6

Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . 46 55,873 0.012 655 0.197 10,987 0.754 42,103 0.038 2,128

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . 47 89,448 0.027 2,422 0.292 26,148 0.649 58,033 0.032 2,845

New Mexico . . . . . . . . . . . . . . . . . . . . . . . 49 39,405 0.021 822 0.175 6,890 0.756 29,802 0.048 1,891

Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . 50 75,705 0.032 2,400 0.270 20,449 0.678 51,351 0.020 1,505

Texas—rest of state . . . . . . . . . . . . . . . . . 51 431,653 0.041 17,785 0.276 119,064 0.661 285,300 0.022 9,504

Texas—El Paso County . . . . . . . . . . . . . . 53 20,871 0.091 1,894 0.143 2,976 0.708 14,776 0.059 1,225

Texas—City of Houston . . . . . . . . . . . . . . 54 67,752 0.040 2,684 0.270 18,310 0.667 45,224 0.023 1,534

Texas—Bexar County . . . . . . . . . . . . . . . 55 38,417 0.054 2,066 0.274 10,514 0.650 24,986 0.022 851

HHS Region 7

Iowa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 54,442 0.025 1,351 0.346 18,820 0.594 32,364 0.035 1,907

Kansas . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 57,727 0.014 796 0.308 17,806 0.660 38,095 0.018 1,030

Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . 58 108,467 0.019 2,087 0.300 32,534 0.648 70,281 0.033 3,565

Nebraska . . . . . . . . . . . . . . . . . . . . . . . . . 59 36,625 0.026 959 0.338 12,385 0.618 22,652 0.017 629

See footnotes at end of table.
Series 1, No. 61  Page 57 

Table 4. Population of children aged 19–35 months on July 1, 2013, for the 56 core estimation areas in National Immunization Survey–Child, 

by telephone status—Con.

Area name

Area 

number

Total 

children

19–35

months

Landline-only

households

Landline and cell-phone 

households

Cell-phone-only 

households

Phoneless

households

Proportion

Children

19–35 

months Proportion

Children 

19–35 

months Proportion

Children

19–35 

months Proportion

Children

19–35 

months

HHS Region 8

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . 60 96,605 0.019 1,813 0.331 31,981 0.631 60,948 0.019 1,863

Montana . . . . . . . . . . . . . . . . . . . . . . . . . . 61 17,205 0.061 1,051 0.243 4,177 0.672 11,561 0.024 416

North Dakota . . . . . . . . . . . . . . . . . . . . . . 62 13,504 0.014 193 0.350 4,725 0.628 8,476 0.008 110

South Dakota . . . . . . . . . . . . . . . . . . . . . . 63 16,347 0.018 301 0.356 5,823 0.599 9,799 0.026 424

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 72,942 0.020 1,461 0.353 25,738 0.606 44,187 0.021 1,556

Wyoming . . . . . . . . . . . . . . . . . . . . . . . . . 65 10,551 0.029 308 0.241 2,545 0.707 7,456 0.023 242

HHS Region 9

Arizona . . . . . . . . . . . . . . . . . . . . . . . . . . 66 123,594 0.056 6,983 0.256 31,608 0.659 81,484 0.028 3,519

California . . . . . . . . . . . . . . . . . . . . . . . . . 68 731,918 0.031 22,665 0.420 307,521 0.531 388,799 0.018 12,933

Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 26,290 0.032 852 0.475 12,498 0.466 12,238 0.027 702

Nevada . . . . . . . . . . . . . . . . . . . . . . . . . . 73 52,403 0.038 1,981 0.378 19,788 0.569 29,827 0.015 807

HHS Region 10

Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 13,751 0.026 352 0.465 6,394 0.498 6,851 0.011 154

Idaho . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 32,070 0.011 342 0.189 6,075 0.772 24,755 0.028 898

Oregon . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 65,631 0.017 1,085 0.305 20,017 0.659 43,251 0.019 1,278

Washington . . . . . . . . . . . . . . . . . . . . . . . 77 127,818 0.033 4,214 0.376 48,062 0.567 72,452 0.024 3,090

... Category not applicable.

NOTES: These population estimates were developed for National Immunization Survey–Child by Nadarajasundaram Ganesh at NORC at the University of Chicago using the methodology and data 

sources described in “National and State Vaccination Coverage Among Adolescents Aged 13–17 Years—United States, 2012;” see reference 19 in report. HHS is U.S. Department of Health and Human 

Services.
Page 58  Series 1, No. 61

Table 5. Annual sample sizes and actual completed interviews from National Immunization Survey–Child, by estimation area: Landline 

random-digit-dialing sample, 2013

Area name

Area

number

Released 

sample size 

(telephone numbers)

Number of 

completed household 

interviews

Number of 

children with 

complete household 

interviews1

Number of 

children with 

adequate 

provider data1

Total in the United States (excluding U.S. territories) . . . . . . . . . . . . . ... 3,395,198 4,741 4,963 3,152

HHS Region 1

Connecticut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 98,244 153 160 110

Massachusetts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 63,970 121 128 76

Maine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 40,716 80 86 63

New Hampshire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 48,175 67 68 48

Rhode Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 96,010 131 137 86

Vermont . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 58,372 95 100 68

HHS Region 2

New Jersey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 89,309 158 163 94

New York—rest of state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 88,073 147 154 93

New York—City of New York . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 97,774 145 149 84

HHS Region 3

District of Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 17,887 21 21 10

Delaware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 72,059 105 111 69

Maryland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 58,650 107 110 68

Pennsylvania—rest of state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 56,104 116 123 78

Pennsylvania—Philadelphia County . . . . . . . . . . . . . . . . . . . . . . . . . 17 76,575 75 81 35

Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 65,179 111 117 73

West Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 60,583 114 121 84

HHS Region 4

Alabama . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 69,659 59 59 32

Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 95,273 92 98 55

Georgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 61,030 74 75 52

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 44,831 68 69 45

Mississippi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 32,496 25 25 14

North Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 63,244 82 89 56

South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 69,361 72 77 49

Tennessee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 53,379 63 66 44

HHS Region 5

Illinois—rest of state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 54,727 71 75 48

Illinois—City of Chicago. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 65,934 87 93 50

Indiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 44,647 65 67 44

Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 68,485 60 62 36

Minnesota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 41,339 72 76 50

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 54,911 59 62 40

Wisconsin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 45,994 75 77 60

HHS Region 6

Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 48,626 39 40 17

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 69,667 68 71 37

New Mexico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 43,171 53 55 31

Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 62,376 82 85 58

Texas—rest of state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 60,608 71 72 48

Texas—El Paso County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 35,925 50 55 42

Texas—City of Houston . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 126,481 91 96 55

Texas—Bexar County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 53,038 55 56 35

HHS Region 7

Iowa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 44,979 60 63 44

Kansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 33,414 57 59 43

Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 40,067 62 67 34

Nebraska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 48,491 90 94 71

HHS Region 8

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 68,590 81 83 50

Montana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 47,364 51 52 44

North Dakota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 32,623 85 89 61

South Dakota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 43,167 75 81 53

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 25,949 47 50 32

Wyoming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 67,537 82 86 49

See footnotes at end of table.
Series 1, No. 61  Page 59 

Table 5. Annual sample sizes and actual completed interviews from National Immunization Survey–Child, by estimation area: Landline 

random-digit-dialing sample, 2013—Con.

Area name

Area

number

Released 

sample size 

(telephone numbers)

Number of 

completed household 

interviews

Number of 

children with 

complete household 

interviews1

Number of 

children with 

adequate 

provider data1

HHS Region 9

Arizona . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 71,289 97 99 55

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 83,635 138 145 80

Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 52,122 68 74 54

Nevada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 58,565 109 119 79

HHS Region 10

Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 58,613 142 144 94

Idaho . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 32,153 38 38 29

Oregon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 80,775 97 103 78

Washington . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 52,983 83 88 65

... Category not applicable.

1

After removing children who became ineligible based on child’s best date of birth.

NOTE: HHS is U.S. Department of Health and Human Services.
Page 60  Series 1, No. 61

Table 6. Annual sample sizes and actual completed interviews from National Immunization Survey–Child, by estimation area: Cell-phone 

random-digit-dialing sample, 2013

Area name

Area 

number

Released 

sample size 

(telephone numbers)

Number of 

completed parental 

interviews

Number of 

children with 

completed parental 

interviews1

Number of 

children with 

adequate 

provider data1

Total in the United States (excluding U.S. territories) . . . . . . . . . . . . . ... 4,537,972 16,818 17,499 10,459

HHS Region 1

Connecticut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 74,265 191 195 103

Massachusetts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 83,059 271 278 165

Maine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 79,616 255 266 161

New Hampshire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 110,043 253 260 163

Rhode Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 97,755 212 223 121

Vermont . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 120,725 325 336 212

HHS Region 2

New Jersey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 87,886 302 311 171

New York—rest of state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 78,059 240 250 133

New York—City of New York . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 108,478 318 331 158

HHS Region 3

District of Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 215,873 353 369 213

Delaware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 93,354 261 274 173

Maryland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 20,113 346 362 219

Pennsylvania—rest of state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 15,272 410 424 240

Pennsylvania—Philadelphia County . . . . . . . . . . . . . . . . . . . . . . . . . 17 278,146 400 425 232

Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 23,122 362 378 201

West Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 92,314 232 245 129

HHS Region 4

Alabama . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 96,276 244 253 134

Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 68,450 276 290 173

Georgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 38,258 204 213 126

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 71,538 228 236 145

Mississippi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 89,589 288 297 166

North Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 69,213 329 341 206

South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 84,084 264 273 158

Tennessee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 86,384 312 326 216

HHS Region 5

Illinois—rest of state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 95,581 452 469 279

Illinois—City of Chicago. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 48,805 196 202 118

Indiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 74,564 336 351 199

Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 80,417 270 280 176

Minnesota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 42,928 233 239 145

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 99,875 348 358 209

Wisconsin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 58,996 251 264 161

HHS Region 6 

Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 81,825 267 279 171

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 116,860 322 343 187

New Mexico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 81,019 335 344 224

Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 104,216 379 393 243

Texas—rest of state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 9,651 510 527 324

Texas—El Paso County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 74,743 294 309 199

Texas—City of Houston . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 95,474 241 252 149

Texas—Bexar County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 126,280 321 338 193

HHS Region 7

Iowa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 50,017 259 270 170

Kansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 59,796 250 253 162

Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 48,989 236 243 154

Nebraska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 57,769 251 262 170

HHS Region 8

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 67,069 349 359 217

Montana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 74,047 262 273 176

North Dakota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 110,350 393 413 242

South Dakota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 36,782 198 209 136

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 35,691 307 322 217

Wyoming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 76,659 218 231 147

See footnotes at end of table.
Series 1, No. 61  Page 61 

Table 6. Annual sample sizes and actual completed interviews from National Immunization Survey–Child, by estimation area: Cell-phone 

random-digit-dialing sample, 2013—Con.

Area name

Area 

number

Released 

sample size 

(telephone numbers)

Number of 

completed parental 

interviews

Number of 

children with 

completed parental 

interviews1

Number of 

children with 

adequate 

provider data1

HHS Region 9

Arizona . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 70,108 325 342 199

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 47,112 350 366 203

Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 51,006 318 328 189

Nevada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 34,415 343 359 219

HHS Region 10

Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 86,013 309 316 205

Idaho . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 47,112 299 307 204

Oregon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 51,006 277 290 197

Washington . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 34,415 243 252 157

... Category not applicable.

1

After removing children who became ineligible based on child’s best date of birth.

NOTE: HHS is U.S. Department of Health and Human Services.
Page 62  Series 1, No. 61

Table 7. Content of the household interview questionnaire from National Immunization 

Survey–Child, 2013 

Section Content

S Screening questions to determine eligibility, roster of eligible children, and availability of shot records

MR Most knowledgeable respondent callback questions 

A1 Vaccination history, asked if shot records are available 

B Vaccination history, asked if shot records are not available 

C Demographic and socioeconomic questions 

D Provider information and request for consent to contact the eligible child’s vaccination providers

E Health insurance coverage questions 

1

Section A was only administered to the sample in the U.S. territory of Guam.
Table 8. Key monitoring statistics for National Immunization Survey–Child: Landline random-digit-dialing sample excluding U.S. territories, 2005–2014

Key indicator 2005 2006 2007 2008 2009 2010 2011 2012 

Random-digit-dialing phase

Total selected telephone numbers in 

released replicates. . . . . . . . . . . . . . . . . . . . . . . . . . . 4,465,261 5,037,830 4,539,367 5,710,803 6,310,629 7,077,661 8,423,688 5,683,234 

Telephone numbers resolved before 

computer-assisted telephone interviewing. . . . . . . . . 1,873,070 2,186,906 1,987,635 2,493,844 2,934,598 3,259,819 3,934,335 2,758,947 

Prefinalization rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.90 43.40 43.80 43.70 46.50 46.10 46.70 48.50 Total telephone numbers released to 

computer-assisted telephone interviewing. . . . . . . . . 2,592,191 2,850,924 2,551,732 3,216,959 3,376,031 3,817,842 4,489,353 2,924,287 

Advance letters mailed. . . . . . . . . . . . . . . . . . . . . . . . . 1,460,066 1,645,109 1,469,436 1,760,771 1,579,190 1,711,459 1,925,791 1,184,323 

Advance letters rate . . . . . . . . . . . . . . . . . . . . . . . . . . . 56.30 57.70 57.60 54.70 46.80 44.80 42.90 40.50 

Resolved telephone numbers1 . . . . . . . . . . . . . . . . . . . 3,721,224 4,197,242 3,763,013 4,698,087 5,228,200 5,897,725 6,992,832 4,780,039 

Resolution rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.30 83.30 82.90 82.30 82.80 83.30 83.00 84.10 

Households identified . . . . . . . . . . . . . . . . . . . . . . . . . 1,085,040 1,137,706 974,586 1,108,491 1,114,670 1,185,219 1,258,093 734,695 Working residential number rate . . . . . . . . . . . . . . . . . 29.20 27.10 25.90 23.60 21.30 20.10 18.00 15.40 

Households successfully screened for 

presence of age-eligible children. . . . . . . . . . . . . . . . 1,006,435 1,029,073 879,207 1,000,840 1,030,376 1,084,421 1,141,212 666,273 

Screener completion rate. . . . . . . . . . . . . . . . . . . . . . . 92.80 90.50 90.20 90.30 92.40 91.50 90.70 90.70 Households with no age-eligible children2 . . . . . . . . . . 974,510 995,113 851,400 971,162 1,001,463 1,057,016 1,113,511 652,145 

Ineligibility rate2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96.80 96.70 96.80 97.00 97.20 97.50 97.60 97.90 

Households with age-eligible children2 . . . . . . . . . . . . 31,925 33,960 27,807 29,678 28,913 27,405 27,701 14,128 

Eligibility rate2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.20 3.30 3.20 3.00 2.80 2.50 2.40 2.10 

Households with age-eligible children with 

completed random-digit-dialing interviews . . . . . . . . 26,867 29,065 24,133 25,257 24,068 22,915 22,642 11,954 

Interview completion rate. . . . . . . . . . . . . . . . . . . . . . . 84.20 85.60 86.80 85.10 83.20 83.60 81.70 84.60 

CASRO response rate3 . . . . . . . . . . . . . . . . . . . . . . . . 65.10 64.50 64.90 63.20 63.70 63.80 61.50 64.50 

Age-eligible children with completed 

random-digit-dialing interviews4. . . . . . . . . . . . . . . . . 27,627 29,880 24,807 25,948 24,809 23,605 23,406 12,325 

Provider-record-check phase

Children with consent obtained to contact 

vaccination providers . . . . . . . . . . . . . . . . . . . . . . . . . 21,692 24,193 19,896 21,004 19,681 18,742 18,611 9,203 

Consent rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78.50 81.00 80.20 80.90 79.30 79.40 79.50 74.70 Immunization history questionnaires 

mailed to providers . . . . . . . . . . . . . . . . . . . . . . . . . . 27,023 30,073 25,170 26,081 25,164 25,407 24,512 11,812 

Immunization history questionnaires or 

medical records returned by providers. . . . . . . . . . . . 23,767 28,427 22,932 24,653 23,626 24,052 23,334 11,322 

Immunization history questionnaire return rate . . . . . . 88.00 94.50 91.10 94.50 93.90 94.70 95.20 95.90 

Children with adequate provider data . . . . . . . . . . . . . 17,563 21,044 17,017 18,430 17,053 16,798 16,919 8,374 Adequate provider data rate . . . . . . . . . . . . . . . . . . . . 63.60 70.40 68.60 71.00 68.70 71.20 72.30 67.90 

1Includes telephone numbers resolved before computer-assisted telephone interviewing.2Prior to the first quarter of 2011 (Q1/2011), children were age eligible if they were aged 19–35 months on the day of the screening interview. Beginning in Q2/2011, children were age eligible if they were or would be 

calendar quarter.

3CASRO is Council of American Survey Research Organizations. The response rate is the product of the resolution rate, screener completion rate, and interview completion rate.4Excludes children with a completed random-digit-dialing interview who were later found to be age ineligible.
Page 64  Series 1, No. 61

Table 9. Key monitoring statistics for National Immunization Survey–Child: Cell-phone random-digit-dialing sample excluding U.S. 

territories, 2011–2014

Key indicator 2011 2012 2013 2014

Random-digit-dialing phase

Total selected telephone numbers in released replicates . . . . . . . . . . . . . . . . . . . 727,860 2,788,756 4,537,972 4,142,841

Resolved telephone numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341,797 1,460,642 2,439,654 2,432,314

Resolution rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47.00 52.40 53.80 58.70

Active personal cell-phone numbers identified . . . . . . . . . . . . . . . . . . . . . . . . . . . 173,090 568,843 900,123 680,212

Active personal cell-phone numbers rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50.60 38.90 36.90 28.00

Active personal cell-phone numbers successfully screened1 . . . . . . . . . . . . . . . . 132,033 440,389 713,754 534,254

Screener completion rate1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76.30 77.50 79.30 78.50

Number of screened households that were not eligible2

 . . . . . . . . . . . . . . . . . . . . 127,435 424,282 689,973 516,570

Ineligibility rate2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96.50 96.20 96.70 96.70

Number of screened households that were eligible2

 . . . . . . . . . . . . . . . . . . . . . . . 4,598 16,707 23,781 17,684

Eligibility rate2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.50 3.80 3.30 3.30

Households with age-eligible children with completed 

random-digit-dialing interviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,237 12,608 17,027 12,837

Interview completion rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70.40 75.50 71.60 72.60

CASRO response rate3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.20 30.60 30.50 33.50

Age-eligible children with completed random-digit-dialing interviews4

. . . . . . . . . . 3,335 13,009 17,499 13,233

Provider-record-check phase

Children with consent obtained to contact vaccination providers . . . . . . . . . . . . . 2,502 9,276 11,744 8,853

Consent rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.00 71.30 67.10 66.90

Immunization history questionnaires mailed to providers . . . . . . . . . . . . . . . . . . . 3,358 12,031 15,097 11,178

Immunization history questionnaires or medical records 

returned by providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,150 11,525 14,491 10,472

Immunization history questionnaire return rate . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.80 95.80 96.00 93.70

Children with adequate provider data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,225 8,313 10,459 7,800

Adequate provider data rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66.70 63.90 59.80 58.90

1

Prior to the second quarter of 2011 (Q2/2011), active personal cell-phone numbers (APCNs) were screened both for cell-phone status to identify cell-phone-only or cell-phone-mainly households and 

for age eligibility to identify cell phones used by adults in households with a child aged 19–35 months. In Q2/2011–Q4/2011, APCNs were screened only to identify adult cell phones in households with 

a child aged 19–35 months i.e., they were not screened for cell-phone status.

2

Prior to Q2/2011, households were eligible if an adult used the cell phone, if the household was cell-phone only or cell-phone mainly, and if the household contained a child aged 19–35 months on the 

day of age-eligibility screening. Beginning Q2/2011, households were eligible if an adult used the cell phone and if the household contained a child that was or would be aged 19–35 months on any day 

in the calendar quarter.

3

CASRO is Council of American Survey Research Organizations. The response rate is the product of the resolution rate, screener completion rate, and interview completion rate.

4

Excludes children with a completed random-digit-dialing interview who were later found to be age ineligible.

Table 10. Annual household response rates for National Immunization Survey–Child: 

Combined landline and cell-phone random-digit-dialing samples excluding U.S. territories, 

2011–2014

Key indicator 2011 2012 2013 2014

Estimated eligible households (HHs) . . . . . . . . . . . . . . . . . . . . . . . . . 49,617 59,702 63,477 55,712

Observed eligible HHs among screened. . . . . . . . . . . . . . . . . . . . 32,299 30,835 29,605 30,907

Estimated eligible HHs from unscreened . . . . . . . . . . . . . . . . . . . 4,267 6,324 6,784 5,950

Estimated eligible HHs from unresolved . . . . . . . . . . . . . . . . . . . . 13,052 22,543 27,088 18,855

Completed HH interviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25,879 24,562 21,819 23,695

HH response rate (percent) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.20 41.20 34.40 42.50
Series 1, No. 61  Page 65 

Table 11. Item nonresponse rates for demographic variables subject to imputation in National Immunization Survey–Child: Landline 

random-digit-dialing sample, 2005–2014

Variable

Item nonresponse rate1

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Education of mother . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 0.7 0.7 0.8 0.8 0.9 0.8 0.8 0.8 1.1

Marital status of mother . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.5

Hispanic origin of child. . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 0.6 0.4 0.4 0.3 0.4 0.4 0.4 0.5 0.5

Hispanic origin of mother . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 0.5 0.3 0.4 0.4 0.4 0.4 0.4 0.6 0.5

Age of mother . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 1.1 0.9 1.0 1.0 1.6 1.5 1.7 2.0 2.6

Number of landline telephone numbers in 

household . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 0.3 0.2 0.3 0.3 0.3 0.3 0.3 0.4 0.4

Interruption in telephone service . . . . . . . . . . . . . . . . . . . 0.4 0.4 0.4 0.3 0.3 0.3 0.3 0.3 0.4 0.5

Length of interruption in landline 

telephone service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.6 0.5 0.5 0.5 0.4 ... ... ... ... ...

Number of cell phones used in the household . . . . . . . . ... ... ... ... ... 1.2 1.3 1.2 1.6 1.6

Number of cell phones usually used by 

child’s parent or guardian . . . . . . . . . . . . . . . . . . . . . . . ... ... ... ... ... 1.2 1.3 1.2 1.5 1.5

Single race of child . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2 ... ... ... ... ... ... ... ... ...

Race of child with multiple-race category . . . . . . . . . . . . 8.4 9.2 7.7 7.4 6.6 5.9 5.0 4.7 4.5 4.3

Single race of mother . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2 9.8 8.5 7.9 7.2 6.5 5.8 5.6 5.6 5.4

Race of mother with multiple-race category . . . . . . . . . . 8.9 9.4 8.1 7.6 6.7 5.9 5.3 5.0 4.7 4.6

Sex of child . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.1 0.0 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.2

First-born status of child . . . . . . . . . . . . . . . . . . . . . . . . . 2.9 3.2 3.0 3.1 3.4 3.0 2.9 3.1 3.6 3.1

Mobility status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.6 0.5 0.5 0.5 0.5 0.7 0.5 0.6 1.0 0.9

True metropolitan statistical area status . . . . . . . . . . . . . ... ... ... ... ... 0.7 0.7 1.0 1.2 1.1

... Category not applicable.

0.0 Quantity more than zero but less than 0.05. 1

All rates exclude U.S. territories.

NOTES: Imputation of the number of cell phones in the household, the number of cell phones usually used by the parent or guardian, and the true metropolitan statistical area status began in 2010. 

Calculation of single race of child ended after 2005. Collection of length of telephone service interruption ended after 2009.

Table 12. Item nonresponse rates for demographic variables subject to imputation in 

National Immunization Survey–Child: Cell-phone random-digit-dialing sample, 2011–2014

Variable

Item nonresponse rate1

2011 2012 2013 2014

Education of mother . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 0.8 0.8 0.9

Marital status of mother . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 0.4 0.4 0.5

Hispanic origin of child. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.4 0.4 0.4 0.5

Hispanic origin of mother . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 0.3 0.4 0.4

Age of mother . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 1.2 1.8 2.4

Number of cell phones used in the household . . . . . . . . . . 0.4 0.6 0.6 0.6

Number of cell phones usually used by 

child’s parent or guardian . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 0.9 0.7 0.7

Race of child with multiple-race category . . . . . . . . . . . . . . 7.2 6.3 6.1 6.4

Single race of mother . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.0 6.9 7.2 7.5

Race of mother with multiple-race category . . . . . . . . . . . . 7.4 6.3 6.3 6.8

Sex of child . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.1 0.1 0.1 0.2

Firstborn status of child . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 2.2 2.6 2.8

Mobility status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.4 0.6 1.0 1.1

True metropolitan statistical area status . . . . . . . . . . . . . . . 1.1 1.1 1.5 1.7

1

All rates exclude U.S. territories.
Page 66  Series 1, No. 61

Table 13. Candidate predictor variables for fitting the response propensity model for whether a child has adequate provider data for 

National Immunization Survey–Child: 2005–2010, excluding U.S. territories

Name of 

variable Description and category

Selected for final model

2005 2006 2007 2008 2009 2010

AGEGRP Age of child (months) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No Yes No No Yes

19–23

24–29 

30–35 

CHILDNM Number of children under age 18 years living in the household . . . . . . . . . . No Yes Yes Yes Yes Yes

1 child

2–3 children

4 or more children

C5 Relationship of the household respondent to the child 

(mother, father, or other) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes Yes Yes

Mother (step, foster, or adoptive) or female guardian

Father (step, foster, or adoptive) or male guardian

Other and missing

EDUC1 Educational status of the mother. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes No Yes

Less than 12 years

12 years

More than 12 years, not college graduate

College graduate

FRSTBRN Firstborn status of child . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . No Yes Yes Yes No Yes

Yes

No

INCPOV1 Poverty status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes Yes Yes

Above poverty level, household income $75,000 or more

Above poverty level, household income less than $75,000

At or below poverty level

Unknown

MAGEGRP Maternal age group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . No Yes Yes Yes Yes Yes

19 and under

20–29 

30 and over

MARITAL Marital status of the mother. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . No No No No Yes No

Widowed, divorced, or separated

Never married

Married

Deceased

MOBIL Mobility status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes Yes Yes

Moved, mother resided in a different state when child was born

Did not move from different state

MSA Relation of household’s location to metropolitan 

statistical area (MSA). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes Yes Yes

In central city of MSA

In MSA, but not in central city

Not in MSA

RACEKID Race or ethnicity of the child . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes Yes Yes

Hispanic

White only, non-Hispanic

Black only, non-Hispanic

American Indian or Alaska Native only, non-Hispanic

Asian, Native Hawaiian or Pacific Islander only, non-Hispanic

Other or multiple race, non-Hispanic

SEX Sex of the child . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . No No No No Yes No

Male

Female

SHOTCARD Household’s use of a “shot card” in reporting immunization status . . . . . . . . Yes Yes Yes Yes Yes Yes

Shot card used during household interview

Shot card not used during household interview
Table 14. Sample sizes and coefficient of variation of weights in National Immunization Survey–Child: 2005–2014, excluding U.S. territories

Weight  Summary statistic 2005 2006 2007 2008 2009 2010 2011 201

Final child-level 

interview weights (RDDWT)

Number of child records. . . . . . . . . . . . . . . . . 27,627 29,880 24,807 25,948 25,241 24,013 26,741 25,3

National CV of weights . . . . . . . . . . . . . . . . . 128.6 134.3 137.9 137.7 143.3 143.7 149.9 15

Minimum estimation area CV of weights . . . . 31.0 39.9 22.6 33.9 25.3 35.2 59.9 4

Median estimation area CV of weights . . . . . 54.4 60.1 63.8 61.5 63.5 57.1 87.9 7

Maximum estimation area CV of weights . . . 83.6 101.9 91.9 112.0 124.3 88.7 140.7 10

Final provider-phase 

weights (PROVWT)

Number of child records. . . . . . . . . . . . . . . . . 17,563 21,044 17,017 18,430 17,313 17,004 19,144 16,6

National CV of weights . . . . . . . . . . . . . . . . . 140.2 141.9 147.1 144.2 152.4 147.0 160.6 16

Minimum estimation area CV of weights . . . . 29.8 37.7 30.7 36.9 30.6 36.7 60.0 4

Median estimation area CV of weights . . . . . 60.1 63.2 67.8 64.5 67.2 60.9 88.8 7

Maximum estimation area CV of weights . . . 99.9 99.2 94.9 113.9 130.0 89.6 139.4 10

NOTE: CV is coefficient of variation and is expressed as a percentage.
Page 68  Series 1, No. 61

Table 15. Candidate predictor variables for fitting the response propensity model for whether a child has adequate provider data for 

National Immunization Survey–Child: 2011–2014, excluding U.S. territories

Name of variable Description and category

Selected for final model

2011 2012 2013 2014

AGEGRP Age of child (months) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No Yes Yes

19–23

24–29

30–35

CHILDNM Number of children under age 18 years living in the household . . . . . . . . . . . . . Yes No No Yes

1 child

2–3 children

4 or more children

C5 Relationship of the household respondent to the child 

(mother, father, or other) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes

Mother (step, foster, or adoptive) or female guardian

Father (step, foster, or adoptive) or male guardian

Other or missing

EDUC1 Educational status of the mother. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes

Less than 12 years

12 years

More than 12 years, not college graduate

College graduate

FRSTBRN Firstborn status of child . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No No Yes

Yes

No

INCPOV1 Poverty status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes

Above poverty level, household income $75,000 or more

Above poverty level, household income less than $75,000

At or below poverty level

Unknown

MAGEGRP Maternal age group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No Yes Yes

19 and under

20–29 

30 and over

MARITAL Marital status of the mother. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No Yes No

Widowed, divorced, or separated

Never married

Married

Deceased

MOBIL Mobility status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . No Yes Yes No

Moved, mother resided in a different state when child was born

Did not move from different state

MSA Relation of household’s location to metropolitan statistical area (MSA) . . . . . . . Yes Yes Yes No

In central city of MSA

In MSA, but not in central city

Not in MSA

RACEKID Race or ethnicity of the child . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes

Hispanic

White only, non-Hispanic

Black only, non-Hispanic

American Indian or Alaska Native only, non-Hispanic

Asian, Native Hawaiian, or Pacific Islander only, non-Hispanic

Other or multiple race, non-Hispanic

SEX Sex of the child . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . No No No No

Male

Female

SHOTCARD Household’s use of a “shot card” in reporting immunization status . . . . . . . . . . . Yes ... ... ...

Shot card used during household interview

Shot card not used during household interview

OWNER Housing tenure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No No No

Owned or being bought

All other (including rented, other arrangements, don’t know, or refused)

TEL_SAMPFRAME Identifies whether the telephone number was selected from 

the landline or cell-phone sampling frame. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes

Landline

Cell phone

AGEGRP*TEL_SAMPFRAME Interaction between AGEGRP and TEL_SAMPFRAME . . . . . . . . . . . . . . . . . . . Yes No Yes Yes

C5*TEL_SAMPFRAME Interaction between C5 and TEL_SAMPFRAME . . . . . . . . . . . . . . . . . . . . . . . . Yes Yes Yes Yes

MAGEGRP*TEL_SAMPFRAME Interaction between MAGEGRP and TEL_SAMPFRAME . . . . . . . . . . . . . . . . . . No No Yes No

RACEKID*TEL_SAMPFRAME Interaction between RACEKID and TEL_SAMPFRAME . . . . . . . . . . . . . . . . . . . Yes No Yes No

See footnotes at end of table.
Series 1, No. 61  Page 69 

Table 15. Candidate predictor variables for fitting the response propensity model for whether a child has adequate provider data for 

National Immunization Survey–Child: 2011–2014, excluding U.S. territories—Con.

Name of variable Description and category

Selected for final model

2011 2012 2013 2014

FRSTBRN*TEL_SAMPFRAME Interaction between FRSTBRN and TEL_SAMPFRAME . . . . . . . . . . . . . . . . . . Yes No No No

CHILDNM*TEL_SAMPFRAME Interaction between CHILDNM and TEL_SAMPFRAME . . . . . . . . . . . . . . . . . . . Yes No No Yes

MARITAL*TEL_SAMPFRAME Interaction between MARITAL and TEL_SAMPFRAME . . . . . . . . . . . . . . . . . . . No No Yes No

EDUC1*TEL_SAMPFRAME Interaction between EDUC1 and TEL_SAMPFRAME . . . . . . . . . . . . . . . . . . . . . Yes Yes No Yes

OWNER*TEL_SAMPFRAME Interaction between OWNER and TEL_SAMPFRAME . . . . . . . . . . . . . . . . . . . . Yes No No No

MSA*TEL_SAMPFRAME Interaction between MSA and TEL_SAMPFRAME . . . . . . . . . . . . . . . . . . . . . . . Yes Yes No No

... Category not applicable.
Table 16. Key monitoring statistics for National Immunization Survey–Teen: Landline random-digit-dialing sample excluding U.S. territories, 2006–2014 Key indicator Quarter 4, 2006 Quarter 4, 2007 2008 2009 2010 2011 2012 

Random-digit-dialing phase Total selected telephone numbers in released replicates. . . . . . . . . . . . . . . . . 341,512 398,683 2,481,132 3,275,206 3,365,921 4,266,170 3,676,083 

Telephone numbers resolved before computer-assisted telephone interviewing . . . . . . . . . . . . . . . . . . . . . . 141,615 168,315 1,091,342 1,524,300 1,556,455 2,002,669 1,780,036 

Prefinalization rate . . . . . . . . . . . . . . . . . . 41.50 42.20 44.00 46.50 46.20 46.90 48.42 

Total telephone numbers released to 

computer-assisted telephone 

interviewing . . . . . . . . . . . . . . . . . . . . . . 199,897 230,368 1,389,790 1,750,906 1,809,466 2,263,501 1,896,047 

Advance letters mailed. . . . . . . . . . . . . . . 118,189 132,870 756,176 809,385 803,790 952,525 758,603 

Advance letters rate . . . . . . . . . . . . . . . . . 59.10 57.70 54.40 46.20 44.40 42.10 40.01 Resolved telephone numbers1 . . . . . . . . . 281,465 327,674 2,040,314 2,707,821 2,798,198 3,538,211 3,086,732 

Resolution rate. . . . . . . . . . . . . . . . . . . . . 82.40 82.20 82.20 82.70 83.10 82.90 83.97 

Households identified . . . . . . . . . . . . . . . 79,085 85,037 481,056 571,039 552,725 622,778 474,801 Working residential number rate . . . . . . . 28.10 26.00 23.60 21.10 19.80 17.60 15.38 

Households successfully 

screened for presence of age-eligible adolescents . . . . . . . . . . . . 64,387 69,289 403,134 485,138 471,817 527,203 403,165 

Screening completion rate. . . . . . . . . . . . 81.40 81.50 83.80 85.00 85.40 84.70 84.91 Households with no age-eligible 

adolescents . . . . . . . . . . . . . . . . . . . . . . 57,838 62,717 367,063 442,724 432,006 485,551 373,569 

Ineligibility rate. . . . . . . . . . . . . . . . . . . . . 89.80 90.50 91.10 91.30 91.60 92.10 92.66 Households with age-eligible 

adolescents . . . . . . . . . . . . . . . . . . . . . . 6,549 6,572 36,071 42,414 39,811 41,652 29,596 

Eligibility rate . . . . . . . . . . . . . . . . . . . . . . 10.20 9.50 8.90 8.70 8.40 7.90 7.34 Households with age-eligible 

adolescents with completed 

random-digit-dialing interviews . . . . . . . 5,481 5,486 30,725 35,004 32,491 33,945 22,853 

Interview completion rate. . . . . . . . . . . . . 83.70 83.50 85.20 82.50 81.60 81.50 77.22 CASRO response rate2 . . . . . . . . . . . . . . 56.20 55.90 58.70 58.00 57.90 57.20 55.06 

Age-eligible adolescents with completed 

random-digit-dialing interviews3. . . . . . . 5,468 5,474 30,681 34,976 32,429 33,891 22,807 

Provider-record-check phase

Adolescents with consent obtained to 

contact vaccination providers . . . . . . . . 4,192 4,114 23,561 26,125 23,738 25,048 16,628 

Consent rate . . . . . . . . . . . . . . . . . . . . . . 76.70 75.20 76.80 74.70 73.20 73.90 72.91 

Immunization history questionnaires 

mailed to providers . . . . . . . . . . . . . . . . 5,851 5,848 33,817 38,329 40,263 42,262 28,879 

Immunization history questionnaires or 

medical records returned by providers . . . . . . . . . . . . . . . . . . . . . . . . 5,220 5,213 31,750 35,960 37,526 39,752 27,444 

Immunization history questionnaire 

return rate . . . . . . . . . . . . . . . . . . . . . . . 89.20 89.10 93.90 93.80 93.20 94.10 95.03 

Adolescents with adequate 

provider data . . . . . . . . . . . . . . . . . . . . . 2,882 2,947 17,835 20,066 19,257 20,848 14,133 

Adequate provider data rate . . . . . . . . . . 52.70 53.80 58.10 57.40 59.40 61.50 61.97 

1Includes telephone numbers resolved before computer-assisted telephone interviewing.2CASRO is Council of American Survey Research Organizations. The response rate is the product of the resolution rate, screener completion rate, and interview completion rate.3Excludes adolescents with a completed random-digit-dialing interview who were later found to be age ineligible.
Series 1, No. 61  Page 71 

Table 17. Key monitoring statistics for National Immunization Survey–Teen: Cell-phone random-digit-dialing sample excluding U.S. 

territories, 2011–2014

Key indicator 2011 2012 2013 2014

Random-digit-dialing phase

Total selected telephone numbers in released replicates . . . . . . . . . . 648,691 1,274,436 3,882,201 3,069,031

Resolved telephone numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304,091 663,110 2,092,383 1,808,334

Resolution rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46.90 52.03 53.90 58.92

Active personal cell-phone numbers identified . . . . . . . . . . . . . . . . . . 153,853 262,183 773,858 502,017

Active personal cell-phone numbers rate . . . . . . . . . . . . . . . . . . . . . . . 50.60 39.54 36.98 27.76

Active personal cell-phone numbers successfully screened1 . . . . . . . 107,967 185,065 565,564 365,720

Screener completion rate1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70.20 70.59 73.08 72.85

Number of screened households that were not eligible2

 . . . . . . . . . . . 100,640 171,029 527,518 340,462

Ineligibility rate2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.20 92.42 93.27 93.09

Number of screened households that were eligible2

 . . . . . . . . . . . . . . 7,327 14,036 38,046 25,258

Eligibility rate2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.80 7.58 6.73 6.91

Households with age-eligible adolescents with 

completed random-digit-dialing interviews . . . . . . . . . . . . . . . . . . . . 4,984 9,007 22,495 18,368

Interview completion rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68.00 64.17 59.13 72.72

CASRO response rate3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.40 23.57 23.29 31.22

Age-eligible adolescents with completed 

random-digit-dialing interviews4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,976 8,985 22,448 18,342

Provider-record-check phase

Adolescents with consent obtained to contact 

vaccination providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,346 6,100 14,579 11,228

Consent rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67.20 67.89 64.95 61.21

Immunization history questionnaires mailed to providers . . . . . . . . . . 5,594 10,758 24,817 17,642

Immunization history questionnaires or medical 

records returned by providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,243 10,192 23,662 16,716

Immunization history questionnaire return rate . . . . . . . . . . . . . . . . . . 93.70 94.74 95.35 94.75

Adolescents with adequate provider data . . . . . . . . . . . . . . . . . . . . . . 2,716 5,066 12,225 9,584

Adequate provider data rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.60 56.38 54.46 52.25

1

In the first quarter of 2011 (Q1/2011), active personal cell-phone numbers (APCNs) were screened both for cell-phone status to identify cell-phone-only or cell-phone-mainly households and for age 

eligibility to identify cell phones used by adults in households with an adolescent aged 13–17. Beginning with Q2/2011 and after, APCNs were screened only to identify adults in households with an 

adolescent aged 13–17 i.e., they were not screened for cell-phone status.

2

In Q1/2011, households were eligible if an adult used the cell phone, if the household was cell-phone only or cell-phone mainly, and if the household contained an adolescent aged 13–17 on the 

day of age-eligibility screening. Beginning Q2/2011, households were eligible if an adult used the cell phone and if the household contained an adolescent aged 13–17 on the day of age-eligibility 

screening.

3

CASRO is Council of American Survey Research Organizations. The response rate is the product of the resolution rate, screener completion rate, and interview completion rate.

4

Excludes adolescents with a completed random-digit-dialing interview who were later found to be age ineligible.

Table 18. Annual household response rates for National Immunization Survey–Teen: 

Combined landline and cell-phone random-digit-dialing samples excluding U.S. territories, 

2011–2014

Key indicator 2011 2012 2013 2014

Estimated eligible households (HHs) . . . . . . . . . . . . . . . . . . . . . . . 81,600 79,727 116,462 91,581

Observed eligible HHs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48,979 43,632 52,326 48,823

Estimated eligible HHs from unscreened . . . . . . . . . . . . . . . . . 10,665 11,108 16,324 12,881

Estimated eligible HHs from unresolved . . . . . . . . . . . . . . . . . . 21,956 24,988 47,812 29,877

Completed HH interviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38,929 31,860 32,652 38,115

HH response rate (percent) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47.7 40.0 28.0 41.6
Page 72  Series 1, No. 61

Table 19. Percentage of adolescents in the population within estimation area for National Immunization Survey–Teen, by telephone status, 

2013 

Area name

Area 

number

Adolescents in 

landline-only households 

as percentage of 

all adolescents in 

estimation area

Adolescents in 

dual-user households 

as percentage of 

all adolescents in 

estimation area

 Adolescents in cellphone-only households 

as percentage of 

all adolescents in 

estimation area

 Adolescents in 

phoneless households 

as percentage of 

all adolescents in 

estimation area

HHS Region 1

Connecticut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.13 70.80 26.26 0.81

Massachusetts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.53 77.87 18.68 0.93

Maine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.17 62.03 34.45 1.36

New Hampshire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 0.71 73.83 24.23 1.23

Rhode Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.79 67.05 28.11 2.05

Vermont . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.93 65.93 29.22 0.92

HHS Region 2

New Jersey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.15 78.84 18.78 1.23

New York—rest of state . . . . . . . . . . . . . . . . . . . . . . . . 10 1.55 72.04 24.93 1.48

New York—City of New York . . . . . . . . . . . . . . . . . . . . 11 2.29 64.98 30.69 2.04

HHS Region 3

District of Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.32 63.95 29.95 1.78

Delaware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1.45 65.32 31.77 1.46

Maryland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 0.56 66.58 31.38 1.48

Pennsylvania—rest of state . . . . . . . . . . . . . . . . . . . . . 16 2.34 64.33 31.65 1.68

Pennsylvania—Philadelphia County . . . . . . . . . . . . . . 17 2.80 55.39 38.83 2.98

Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 1.40 65.09 31.91 1.61

West Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.23 52.17 43.25 2.36

Alabama . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.18 50.34 45.66 1.82

HHS Region 4

Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.68 47.15 47.68 2.49

Georgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 1.54 51.23 44.85 2.39

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 1.68 48.72 47.23 2.37

Mississippi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2.21 40.29 55.45 2.05

North Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 1.86 55.27 41.33 1.54

South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 1.72 47.30 48.76 2.22

Tennessee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 1.01 49.49 47.63 1.87

HHS Region 5

Illinois—rest of state . . . . . . . . . . . . . . . . . . . . . . . . . . 34 0.85 58.70 39.11 1.34

Illinois—City of Chicago. . . . . . . . . . . . . . . . . . . . . . . . 35 1.84 55.01 41.46 1.69

Indiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.97 49.02 43.83 3.18

Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 2.73 53.05 42.34 1.88

Minnesota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 1.24 62.07 35.54 1.15

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 1.63 54.95 40.96 2.47

Wisconsin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 1.54 55.45 41.08 1.93

HHS Region 6

Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 1.27 38.38 57.74 2.61

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 2.75 51.59 43.75 1.91

New Mexico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 5.94 40.50 49.51 4.05

Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 0.98 47.64 50.27 1.10

Texas—rest of state . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 2.44 41.78 53.95 1.83

Texas—City of Houston . . . . . . . . . . . . . . . . . . . . . . . . 54 1.97 44.79 51.30 1.94

Texas—Bexar County . . . . . . . . . . . . . . . . . . . . . . . . . 55 1.40 39.82 56.95 1.82

HHS Region 7

Iowa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 0.94 50.13 46.72 2.20

Kansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 2.69 49.35 46.05 1.91

Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 1.26 43.89 52.20 2.64

Nebraska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 1.71 56.78 40.37 1.14

HHS Region 8

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 2.20 57.64 38.58 1.58

Montana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 3.46 51.24 42.28 3.02

North Dakota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 3.62 52.27 43.60 0.51

South Dakota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 1.88 61.11 35.49 1.52

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 0.26 54.55 43.80 1.40

Wyoming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 4.64 49.72 44.18 1.46

See footnotes at end of table.
Series 1, No. 61  Page 73 

Table 19. Percentage of adolescents in the population within estimation area for National Immunization Survey–Teen, by telephone status, 

2013—Con.

Area name

Area 

number

Adolescents in 

landline-only households 

as percentage of 

all adolescents in 

estimation area

Adolescents in 

dual-user households 

as percentage of 

all adolescents in 

estimation area

 Adolescents in cellphone-only households 

as percentage of 

all adolescents in 

estimation area

 Adolescents in 

phoneless households 

as percentage of 

all adolescents in 

estimation area

HHS Region 9

Arizona . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 4.28 43.63 50.26 1.82

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4.92 57.34 36.53 1.21

Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 0.77 53.71 43.83 1.69

Nevada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 4.32 55.05 39.04 1.59

HHS Region 10

Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 1.82 79.39 18.10 0.69

Idaho . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 0.98 45.80 51.34 1.87

Oregon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 2.17 53.08 43.30 1.46

Washington . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 2.47 57.33 38.88 1.32

NOTES: Data exclude all U.S. territories. HHS is U.S. Department of Health and Human Services.

SOURCE: Estimates derived by Nadarajasundaram Ganesh at NORC at the University of Chicago using statistical methods similar to those reported in “Wireless Substitution: State-level Estimates 

From the National Health Interview Survey, January 2007–June 2010;” see reference 41 in report.
Page 74  Series 1, No. 61

See footnotes at end of table.

Table 20. Topical modules conducted as part of National Immunization Survey–Child and –Teen

Topical module1 Sample sizes of children2

Period of administration

(quarter/year) Purpose

National Immunization Survey–Child 

Knowledge, Attitudes, and 

Practices

5,780 children with completed modules Q1–Q4/2001 Provided data on parental concerns about childhood 

vaccinations. Conducted as a follow-up interview 

with parents who responded to the 2000–2001 NIS–

Child, as well as a mail survey of 1,076 providers of 

the NIS–Child children to gather their attitudes and 

practices.

Health Insurance and 

Ability to Pay for Vaccines 

30,741 children with completed modules, 24,596 with 

adequate provider data

Q3/2001–Q4/2002 Provided data on economic and health insurancerelated barriers to vaccination and vaccination 

coverage levels and to evaluate vaccination coverage 

for Vaccines for Children-eligible children.

Parental Knowledge and 

Experiences

5,273 children with completed modules, 7,810 with 

adequate provider data

Q3/2001–Q4/2002 Provided data on parental concerns about vaccine 

safety and the impact of those concerns on 

vaccination practices.

Daycare, Breastfeeding 

Practices, and WIC3

9,908 children with completed modules, 4,179 with 

adequate provider data

Q3/2001–Q4/2002 Provided data to determine vaccination coverage 

among WIC3

-eligible children.

Vaccine Shortage 2,840 children with completed modules, 2,247 with 

adequate provider data

Q2–Q4/2003 Provided data on the 2001–2005 shortages of the 

pneumococcal vaccine.

Vaccine Safety 2,936 children with completed modules, 2,287 with 

adequate provider data

Q2–Q4/2003 Provided data on how parents’ concerns about vaccine 

safety might be addressed to increase vaccination 

coverage among children.

Influenza 30,682 children with completed modules, 20,599 

with adequate provider data

Q1–Q4/2004 Provided data on influenza vaccination history.

Health Insurance4 Q1–Q4/2006: 24,712 children with completed 

modules, 20,890 with adequate provider data

Q1–Q4/2006–2014 Provided data to determine the degree to which NISsampled children are entitled to access vaccines 

through their state’s Vaccine’s for Children Program. 

These data helped identify children covered by 

private insurance, public insurance (Medicaid or 

state Children's Health Insurance Program), military 

insurance (TRICARE), or Indian Health Service.

Q1–Q4/2007: 20,618 children with completed 

modules, 16,903 with adequate provider data

Q1–Q4/2008: 21,650 children with completed 

modules, 18,254 with adequate provider data

Q1–Q4/2009: 20,059 children with completed 

modules, 16,863 with adequate provider data

Q1–Q4/2010: 18,9965

 children with completed 

modules, 16,5915

 with adequate provider data 

Q1–Q4/2011: 21,424 children with completed 

modules, 18,927 with adequate provider data

Q1–Q4/2012: 18,607 children with completed 

modules, 16,503 with adequate provider data

Q1–Q4/2013: 15,379 children with completed 

modules, 13,293 with adequate provider data

Q1–Q4/2014: 17,050 children with completed 

modules, 14,629 with adequate provider data

Socioeconomic Status 8,768 children with completed modules, 7,450 with 

adequate provider data

Q1–Q2/2008 Provided data on socioeconomic status indicators 

related to racial, ethnic, and poverty disparities in 

vaccination coverage.

Parental Concerns Q3/2008–Q4/2009: 29,509 children with completed 

modules, 24,875 with adequate provider data

Q3/2008–Q4/2009; 

Q2–Q4/2011

Provided data on parents’ attitudes about vaccines, 

decisions to delay or refuse vaccine administration, 

Q2–Q4/2011: 13,921 children with completed and reasons for delaying or refusing vaccines. 

modules, 12,259 with adequate provider data
Series 1, No. 61  Page 75 

Table 20. Topical modules conducted as part of National Immunization Survey–Child and –Teen—Con.

Topical module1 Sample sizes of children2

Period of administration

(quarter/year) Purpose

National Immunization Survey–Teen 

Health Insurance4 Q4/2006: 4,356 children with completed modules, 

2,872 with adequate provider data

Q4/2006; Q4/2007; 

Q1–Q4/2008–2014

Provided data to determine the degree to which 

NIS–Teen-sampled children are entitled to access 

vaccines through their state’s Vaccines for Children 

Program. These data helped identify teenagers 

covered by private insurance, public insurance 

(Medicaid or state Children's Health Insurance 

Program), military insurance (TRICARE), or Indian 

Health Service.

Q4/2007: 4,232 children with completed modules, 

2,928 with adequate provider data

Q1–Q4/2008: 24,668 children with completed 

modules, 17,738 with adequate provider data

Q1–Q4/2009: 26,945 children with completed 

modules, 19,921 with adequate provider data

Q1–Q4/2010: 24,4385

 children with completed 

modules, 19,0645

 with adequate provider data 

Q1–Q4/2011: 29,243 children with completed 

modules, 23,324 with adequate provider data

Q1–Q4/2012: 23,316 children with completed 

modules, 19,049 with adequate provider data

Q1–Q4/2013: 22,127 children with completed 

modules, 17,986 with adequate provider data

Q1–Q4/2014: 24,874 children with completed 

modules, 20,540 with adequate provider data

Parental Attitudes 10,808 children with completed modules, 8,490 

with adequate provider data5

Q3–Q4/2010 A project sponsored by the American Recovery and 

Reinvestment Act of 2009, provided data on parents’ 

perceptions about vaccines for their teenaged 

children, parents’ satisfaction with their experience 

getting their teenagers vaccinated, and influences on 

parents’ decision to vaccinate their teenaged children 

and delay or refuse vaccines. 

1

Data from these topical modules are not released for public use. However, access to the restricted data for special analyses may be available by submitting a proposal to the National Center for Health 

Statistics Research Data Center (available from: https://www.cdc.gov/rdc). 2

Sample sizes exclude U.S. territories.

3

Women, Infants, and Children Program

4

Beginning in 2007, data were imputed to be nonmissing for all children with adequate provider data; the sample counts of children with a completed Health Insurance Module presented in this table 

are preimputation.

5

Counts for 2010 exclude the 2010 National Immunization Survey cell-phone sample pilot study.

Table 21. Data-processing steps for National Immunization Survey–Child and –Teen, 

2005–2014

Step Description

1 Post-CATI1

 data editing and summarization

2 Immunization history questionnaire data processing

3 Matching sheet review

4 Derivation of composite variables 

5 Imputation of missing values

6 Final data file production

1

Computer-assisted telephone interview.
Page 76  Series 1, No. 61

Table 22. Editing limits for vaccination date that trigger a matching sheet review: National Immunization Survey–Child and –Teen, 2014

Vaccine category Vaccine type Flag for review if:

National Immunization Survey–Child

DTaP1

 and DTP2 DTaP 1st shot given before DOB plus 38 days

4th shot given before DOB plus 361 days

Less than 24 days between 1st and 2nd shots

Less than 24 days between 2nd and 3rd shots

Less than 119 days between 3rd and 4th shots

Polio IPV 1st shot given before DOB plus 38 days

Less than 24 days between 1st and 2nd shots

Less than 24 days between 2nd and 3rd shots

Measles-containing All types 1st shot given before DOB plus 361 days

Less than 24 days and not zero days between 1st meningococcal conjugate vaccination 

shot and 1st varicella shot

Hepatitis B All types 3rd shot given before DOB plus 120 days

4th shot given before DOB plus 180 days

Less than 24 days between 1st and 2nd shots

Less than 52 days between 2nd and 3rd shots

Varicella All types 1st shot given before DOB plus 180 days

Less than 24 days and not zero days between 1st varicella shot and 1st meningococcal 

conjugate vaccination shot

National Immunization Survey–Teen 

Td and Tdap3 Td Any shot before 7 years

Td/Tdap unknown type Less than 4 weeks between 1st and 2nd shots

Less than 8 weeks between 2nd and 3rd shots

Tdap Any shot before 10 years

Hepatitis B HepB–Hib4 Less than 24 days between 1st and 2nd shots

0.5 ml Recombivax 3rd shot given before DOB plus 120 days

Engerix Less than 52 days between 2nd and 3rd shots

HepB only, unknown type 4th shot given before DOB plus 180 days

HepB-containing, unknown type

1.0 ml Recombivax Less than 4 months between 1st and 2nd shots

Measles-containing All types 1st shot given before DOB plus 361 days

Less than 4 weeks between 1st and 2nd shots

Varicella All types 1st shot given before DOB plus 365 days

Less than 4 weeks between 1st and 2nd shots

Meningococcal MenACWY Any shot before DOB plus 11 years

Any shot before January 14, 2005

Hepatitis A All types 1st shot given before DOB plus 365 days

Less than 6 months between 1st and 2nd shots

HPV5 All types 1st shot given before DOB plus 9 years

Less than 4 weeks between 1st and 2nd shots

Less than 12 weeks between 2nd and 3rd shots

Any shot before June 8, 2006

1

Diphtheria and tetanus toxoids and acellular pertussis vaccine.

2

Diphtheria and tetanus toxoids and pertussis vaccine.

3

Tetanus and diphtheria toxoids vaccine.

4

Haemophilus influenzae type b 5

Human papillomavirus vaccine. 

NOTE: DOB is date of birth.
Series 1, No. 61  Page 77 

Table 23. Quality assurance in imputation for National Immunization Survey–Child and –Teen, 2005–2014

Key step Description Quality assurance task

Assess the need for imputation Identify the variables that need to be imputed for weighting or 

analysis purposes

Confer with weighting team to determine imputation needs

View frequencies of these variables to understand distributions 

and level of missingness

Obtain group consensus on scope of imputation process

Determine class and sort variables to 

use in imputation of each variable

Create logistic-regression models for binary variables or 

cumulative-logistic or multinomial models for multilevel 

variables

Ensure that the correct model type is chosen based on 

variable of interest

Identify necessary class variables Choose class variables to ensure consistency in imputed 

values where necessary

Create list of candidate sort variables Document class and sort variables for records and future use

Fit the model(s) via stepwise model selection to obtain the sort 

variables 

Re-evaluate class and sort variables periodically

Impute missing values Run the imputation SAS macro for each imputation Statistician runs a parallel imputation and ensures that:

Production and parallel imputed values agree

All variables that should have been imputed now have 

nonmissing values

The variable values for unimputed records did not change

The distribution of imputed values is similar to the 

distribution of unimputed values 

New imputed values are within valid ranges

No case donated a value to more than four recipients

Table 24. Quality assurance in weighting for National Immunization Survey–Child and –Teen, 2005–2014

Key step Description Quality assurance task

Assess the need for weighting Identify all weights required for analytical purposes Confer with sampling team and analysis team to determine 

weighting needs

Implement alternative weighting approaches to assess the 

potential pros and cons of each approach

Assess alternative weighting approaches

Obtain group consensus on scope of weighting process

Check and prepare all required 

weighting inputs

Derive population control totals for weighting Compare current year’s control totals with previous year’s 

control totals to ensure no abrupt changes

Derive true area of residence for each household with a 

completed interview

Ensure the availability of all required input variables for 

weighting and proper assignment of disposition codes to 

each released case

Identify the list of required input variables for weighting Document control total and true area derivation

Senior weighting statistician reviews all relevant work

Set up detailed weighting plan Write a weighting plan that includes a description of each step 

of weighting

Weighting team meets to review each weighting step and 

check coherence of the whole plan

Identify any potential issues in the current plan and discuss 

with senior weighting statisticians 

Produce weights Implement weighting and produce weights Weighting statistician implements weighting, documenting all 

outputs and logs and creating weighting summaries.

Create weight summary files, summarizing key statistics for 

each weight variable

Senior weighting statistician runs a parallel check of 

weighting, ensuring that: 

Each weighting step is implemented according to the 

weighting plan

Each step has sufficient cases to warrant stable weighting 

adjustment

All cases that should have weights have nonmissing and 

correctly assigned weights

The summation of the final random-digit-dialing household 

weights and final provider-phase weights agree with the 

control totals for each calibration dimension

The weight variation is within valid and expected range 

Produce weighted vaccine coverage 

rates

Generate weighted vaccine coverage rates using the current 

year’s data 

Weighting statistician compares current weighted vaccine 

coverage rates with similar vaccination coverage rates from 

prior years

Weighting quality control meeting Weighting team meets with senior statisticians to discuss the 

weighting summaries

Review statistics of each weight and address any concerns
Page 78  Series 1, No. 61

Table 25. Percentage of children in National Immunization Survey–Child also included in 19 

immunization information systems, 2008–2011

Status of NIS–Child1 children Minimum percent Maximum percent

Not matched in IIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 31.8

Matched in IIS, and IIS contains no vaccination data . . . . . . . . . – 17.2

Matched in IIS, and IIS vaccination data are too 

incomplete to determine child’s up-to-date status . . . . . . . . . . . 0.3 8.2

Matched in IIS, and IIS vaccination data are adequate to 

determine child’s up-to-date status . . . . . . . . . . . . . . . . . . . . . . 61.4 98.5

– Quantity zero.

1

NIS is National Immunization Survey.

NOTES: The 19 studies represent 15 distinct immunization information systems (IIS) (some studied in multiple years). Participation 

by an IIS in the NIS–IIS match studies was by self-selection. State or local area immunization program grantees and awardees 

requested that some of their grant or cooperative agreement funds be used for this purpose. The results from these studies are not 

generalizable across all IIS or across all years. Percentages are based on the set of children for whom consent was given to contact 

the IIS.

SOURCE: National Immunization Survey–Immunization Information Systems Match Study, 2008–2011.

Table 26. Minimum and maximum differences in vaccination coverage rates between National Immunization Survey–Child, 19 immunization 

information systems, and synthesized National Immunization Survey and immunization information systems, 2008–2011

Summary measure

Differences for 4:3:1:3:3:1 vaccination series

(percentage points)

Differences for 4 or more doses of

DTaP (percentage points)

NIS–Child-IIS

Synthesized NIS 

and IIS-NIS–Child

Synthesized NIS 

and IIS-IIS NIS–Child-IIS

Synthesized NIS 

and IIS-NIS–Child

Synthesized NIS 

and IIS-IIS

Minimum . . . . . . . . . . . . . . . . . . . . . . . . . −8.2 −1.5 0.4 –6.6 −1.5 −2.4

Maximum . . . . . . . . . . . . . . . . . . . . . . . . . 50.8 11.9 51.9 50.8 9.0 49.3

NOTES: DTaP is diphtheria and tetanus toxoids and acellular pertussis vaccine. NIS is National Immunization Survey. IIS is immunization information systems. The 19 studies represent 15 distinct IIS 

(some studied in multiple years). Participation by an IIS in the NIS–IIS match studies was by self-selection. State or local area immunization program grantees and awardees requested that some of 

their grant or cooperative agreement funds be used for this purpose. The results from these studies are not generalizable across all IIS or across all years.
Series 1, No. 61  Page 79 

Table 27. Estimated vaccination coverage rates (percent) and corresponding 95% 

confidence intervals for children aged 19–35 months: National Immunization Survey–Child 

and address-based sample pilot, 2009

Vaccine

National Immunization 

Survey—Child

(n = 17,063)

Address-based 

sample pilot

(n = 367)

4 or more DTaP1 . . . . . . . . . . . . . . . . . . . . . . . . . . 83.9 (±1.0) 81.8 (±5.8)

3 or more polio2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.8 (±0.7) 90.5 (±4.0)

1 or more MMR3 . . . . . . . . . . . . . . . . . . . . . . . . . . 90.0 (±0.8) 89.4 (±4.1)

3 or more Hib4

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.6 (±1.0) 80.3 (±5.7)

3 or more HepB5 . . . . . . . . . . . . . . . . . . . . . . . . . . 92.4 (±0.7) 89.1 (±4.5)

1 or more Var6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89.6 (±0.8) 90.5 (±3.8)

3 or more PCV7

 . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.6 (±0.7) 88.5 (±4.7)

4 or more PCV8

 . . . . . . . . . . . . . . . . . . . . . . . . . . . 80.4 (±1.1) 79.0 (±5.7)

4:3:1 series9

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81.5 (±1.1) 78.7 (±6.0)

4:3:1:3 series10 . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.4 (±1.2) 69.8 (±6.6)

4:3:1:3:3 series11 . . . . . . . . . . . . . . . . . . . . . . . . . . 71.9 (±1.2) 65.3 (±6.9)

4:3:1:3:3:1 series12 . . . . . . . . . . . . . . . . . . . . . . . . 69.9 (±1.2) 63.7 (±7.0)

4:3:1:3:3:1:3 series13 . . . . . . . . . . . . . . . . . . . . . . . 69.0 (±1.2) 61.2 (±7.0)†

4:3:1:3:3:1:4 series14 . . . . . . . . . . . . . . . . . . . . . . . 63.6 (±1.3) 57.0 (±7.2)

1+HepA series15 . . . . . . . . . . . . . . . . . . . . . . . . . . 75.0 (±1.1) 73.2 (±6.4)

2+HepA series16 . . . . . . . . . . . . . . . . . . . . . . . . . . 46.6 (±1.4) 48.0 (±7.3)

†

Statistically different from National Immunization Survey–Child estimate at the 95% confidence level.

1

Four or more doses of any diphtheria and tetanus toxoids and pertussis vaccines including diphtheria and tetanus toxoids, and any 

acellular pertussis vaccine (DTaP, DTP, or DT).

2

Three or more doses of any poliovirus vaccine.

3

One or more doses of measles-mumps-rubella vaccine.

4

Three or more doses of Haemophilus influenzae type b vaccine. 5

Three or more doses of hepatitis B vaccine.

6

One or more doses of varicella at or after child’s first birthday, unadjusted for history of varicella illness.

7

Three or more doses of pneumococcal conjugate vaccine.

8

Four or more doses of pneumococcal conjugate vaccine.

9

Four or more doses of DTaP, 3 or more doses of poliovirus vaccine, and 1 or more doses of any MMR.

10Vaccine series 4:3:1 and 3 or more doses of Hib.

11Vaccine series 4:3:1:3 and 3 or more doses of HepB.

12Vaccine series 4:3:1:3:3 and 1 or more doses of varicella vaccine.

13Vaccine series 4:3:1:3:3:1 and 3 or more doses of PCV. 

14Vaccine series 4:3:1:3:3:1 and 4 or more doses of PCV.

15One or more doses of hepatitis A vaccine.

16Two or more doses of hepatitis A vaccine.

NOTE: No correction for multiple statistical testing was employed.

Table 28. Vaccination coverage rates (percent) and corresponding 95% confidence 

intervals for children aged 19–35 months for each recommended childhood vaccine, by 

survey: National Immunization Survey–American Community Survey and Florida National 

Immunization Survey–Child, 2009

Vaccine

Florida National 

Immunization

Survey–Child

(n = 326)

National Immunization 

Survey–American 

Community Survey 

(n = 745)

4 or more DTaP (diphtheria and tetanus toxoids and 

acellular pertussis) . . . . . . . . . . . . . . . . . . . . . . . . . 88.1 (±5.5) 80.8 (±5.5)

3 or more polio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.8 (±4.7) 90.7 (±3.8)

3 or more Hib (Haemophilus influenzae type b) . . . . 86.7 (±5.9) 88.8 (±4.0)

3 or more HepB (hepatitis B) . . . . . . . . . . . . . . . . . . . 91.6 (±4.8) 91.9 (±3.3)

1 or more Var (varicella) after age 12 months . . . . . . 94.2 (±3.9)1 87.6 (±4.3)

4 or more PCV (pneumococcal) . . . . . . . . . . . . . . . . 76.4 (±7.3) 79.0 (±5.5)

2 or more HepA (hepatitis A) . . . . . . . . . . . . . . . . . . . 39.7 (±8.3) 34.7 (±6.4)

RV2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.6 (±8.3) 43.6 (±6.7)

Seasonal influenza . . . . . . . . . . . . . . . . . . . . . . . . . . 16.7 (±6.4)1 7.7 (±3.6)

1

Estimated percentage is significantly different from corresponding percentage in the other survey, p ≤ 0.05. 2

Two or more doses of Rotarix (RVI) or 3 or more doses of RotaTeq (RV5).
Page 80  Series 1, No. 61

Table 29. Differences in vaccination coverage rates (percent) and 95% confidence intervals 

for children aged 19–35 months between National Immunization Survey–Child and 

immunization information systems samples: Quarter 1–Quarter 2, 2008 

 Vaccine

Differences1

 in vaccination coverage rates for 

National Immunization Survey–Child and 

immunization information systems

State A State B

4 or more DTaP (diphtheria and tetanus toxoids and 

acellular pertussis) . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 (± 10.7) 1.6 (± 8.3)

3 or more polio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.6 (± 9.0) –1.5 (± 3.6)

1 or more MMR (measles, mumps, and rubella) . . . . . –1.2 (± 8.3) 2.1 (± 5.7)

3 or more Hib (Haemophilus influenzae type b) . . . . . –0.9 (± 6.0) –1.1 (± 3.9)

3 or more HepB (hepatitis B) . . . . . . . . . . . . . . . . . . . . –2.8 (± 5.6) –0.2 (± 4.0)

1 or more Var (varicella). . . . . . . . . . . . . . . . . . . . . . . . 2.6 (± 8.9) 1.6 (± 6.1)

4:3:1:3:3:12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 (± 11.1) 1.0 (± 9.1)

1

No differences were statistically significant at the 0.05 level.

2

The vaccine series of 4 or more DTaP/DTP/DT, 3 or more polio, 1 or more MMR, 3 or more Hib doses of any type, 3 or more 

HepB doses, and 1 or more varicella doses given at age 12 months and over. DTP is diphtheria and tetanus toxoids and pertussis 

vaccine; DT is diphtheria and tetanus toxoids vaccine.

Table 30. Comparison of response rates in National Immunization Survey–Child and National Health Interview Survey: 2009–2013, excluding 

U.S. territories

Year

National Immunization Survey–Child

Landline sample Cell-phone sample National Health Interview Survey

Household-phase 

response rate 

(percent)

Rate of children with 

adequate provider 

data (percent)

Household-phase 

response rate 

(percent)

Rate of children with 

adequate provider 

data (percent)

Sample child 

response rate 

(percent)

Rate of children with 

adequate provider 

data (percent)

2009. . . . . . . . . . . . . . . . . . 63.7 68.7 ... ... 73.4 58.2

2010. . . . . . . . . . . . . . . . . . 63.8 71.2 25.91 61.0 70.7 58.2

2011 . . . . . . . . . . . . . . . . . . 61.5 72.3 25.2 66.7 74.6 63.6

2012. . . . . . . . . . . . . . . . . . 64.5 67.9 30.6 63.9 69.7 59.2

2013. . . . . . . . . . . . . . . . . . 62.3 63.5 30.5 59.8 69.0 59.72

... Category not applicable.

1

Results are for the fourth quarter 2010 (Q4/2010) national cell-phone random-digit-dialing pilot sample.

2

Results are for Q1–Q3/2013. The National Health Interview Survey–Provider Record Check (NHIS–PRC) was not conducted in Q4/2013.

SOURCES: Household-phase response rates and rates of children with adequate provider data for National Immunization Survey–Child are available in the annual public-use files (https://www.

cdc.gov/nchs/nis/data_files.htm). NHIS child response rates are available in Appendix II of the 2013 public-use file (ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Dataset_Documentation/NHIS/2013/

srvydesc.pdf). NHIS rates of children with adequate provider data are computed using the operational results of the NHIS–PRC.
Series 1, No. 61  Page 81 

Table 31. National vaccination coverage rates for children aged 19–35 months in National Immunization Survey–Child and National Health 

Interview Survey–Provider Record Check: Quarter 1–Quarter 4, 2009

Vaccine

NIS–Child1

 vaccination

coverage rate

(95% confidence interval),

n = 33,851 

NHIS–PRC vaccination

coverage rate

(95% confidence interval),

n = 2,022

NIS–Child-NHIS–PRC

percent difference in

vaccination coverage rates

(95% confidence interval)

4 or more DTaP (diphtheria and tetanus toxoids and

acellular pertussis) doses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84.2 (± 0.7) 81.1 (± 2.2) 3.0 (± 2.3)2

3 or more polio doses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.0 (± 0.5) 91.3 (± 1.6) 1.7 (± 1.7)2

1 or more measles-mumps-rubella doses . . . . . . . . . . . . . . . . . . . . . 90.7 (± 0.6) 89.7 (± 1.7) 1.0 (± 1.8) 

3 or more Hib (Haemophilus influenzae type b) doses . . . . . . . . . . . 86.9 (± 0.7) 85.4 (± 2.0) 1.5 (± 2.1)

3 or more HepB (hepatitis B) doses . . . . . . . . . . . . . . . . . . . . . . . . . 92.1 (± 0.5) 90.3 (± 1.7) 1.8 (± 1.7)2

1 or more Var (varicella) doses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90.0 (± 0.6) 89.6 (± 1.6) 0.4 (± 1.7)

3 or more PCV (pneumococcal) doses . . . . . . . . . . . . . . . . . . . . . . . 92.6 (± 0.5) 91.7 (± 1.5) 1.0 (± 1.6)

4:3:1:3:3:1:33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.5 (± 0.9) 68.6 (± 2.5) 2.9 (± 2.7)2

1

Single-frame landline random-digit-dialing estimates. 

2

Significant at the 0.05 level.

3

The vaccine series of 4 or more DTaP/DTP/DT, 3 or more polio, 1 or more MMR, 3 or more Hib doses of any type, 3 or more HepB doses, 1 or more varicella doses given at age 12 months and over, 

and 3 or more PCV doses. DTP is diphtheria and tetanus toxoids and pertussis vaccine; DT is diphtheria and tetanus toxoids vaccine.

NOTES: NIS is National Immunization Survey. NHIS–PRC is National Health Interview Survey–Provider Record Check.

Table 32. National vaccination coverage rates for children aged 19–35 months in National Immunization Survey–Child and National Health 

Interview Survey–Provider Record Check: Quarter 1–Quarter 4, 2010 

Vaccine

NIS–Child1

 vaccination

coverage rate

(95% confidence interval),

n = 18,002

NHIS–PRC vaccination

coverage rate

(95% confidence interval),

n = 978

NIS–Child-NHIS–PRC

percent difference in

vaccination coverage rates

(95% confidence interval)

4 or more DTaP (diphtheria and tetanus toxoids and 

acellular pertussis) doses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.6 (± 1.4) 83.4 (± 2.7) –0.8 (± 3.0)

3 or more polio doses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.3 (± 0.8) 93.4 (± 1.8) 0.0 (± 2.0)

1 or more measles-mumps-rubella (MMR) doses . . . . . . . . . . . . . . . 90.4 (± 1.0) 90.2 (± 2.2) 0.3 (± 2.4)

3 or more Hib (Haemophilus influenzae type b) doses . . . . . . . . . . . 91.2 (± 1.0) 91.7 (± 2.0) –0.5 (± 2.2)

3 or more HepB (hepatitis B) doses . . . . . . . . . . . . . . . . . . . . . . . . . 91.1 (± 1.0) 92.0 (± 1.9) –1.0 (± 2.2)

1 or more Var (varicella) doses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89.9 (± 1.0) 89.3 (± 2.3) 0.6 (± 2.5)

3 or more PCV (pneumococcal) doses . . . . . . . . . . . . . . . . . . . . . . . 92.5 (± 0.9) 92.4 (± 2.0) 0.1 (± 2.2)

4:3:1:3:3:1:32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.8 (± 1.5) 74.1 (± 3.2) –1.2 (± 3.6)

0.0 Quantity more than zero but less than 0.05.

1

Dual-frame landline and cell-phone random-digit-dialing estimates. 

2

The vaccine series of 4 or more DTaP/DTP/DT, 3 or more polio, 1 or more MMR, 3 or more Hib doses of any type, 3 or more HepB doses, 1 or more varicella doses given at age 12 months and over, 

and 3 or more PCV doses. DTP is diphtheria and tetanus toxoids and pertussis vaccine; DT is diphtheria and tetanus toxoids vaccine.

NOTES: NIS is National Immunization Survey. NHIS–PRC is National Health Interview Survey–Provider Record Check.
Page 82  Series 1, No. 61

Table 33. Key indicators for National Immunization Survey–Adult: 2007, excluding U.S. 

territories

Key indicators

National Health 

Interview 

Survey sample

Age-targeted 

sample

Combined 

sample

Estimated eligible households (HHs) . . . . . . . . . . . . . . . . . . . . 8,666 14,119 23,157

Observed eligible HHs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,743 5,793 9,536

Estimated eligible HHs from unresolved . . . . . . . . . . . . . . . . 2,820 5,059 8,244

Estimated eligible HHs from unscreened . . . . . . . . . . . . . . . 2,103 3,267 5,377

Completed HH interviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,899 4,156 7,055

CASRO1

 HH response rate (percent) . . . . . . . . . . . . . . . . . . . 33.5 29.4 30.5

1

Council of American Survey Research Organizations.

Table 34. Key indicators for National H1N1 Flu Survey at end of influenza season: 2009, 

excluding U.S. territories

Key indicators

Landline 

sample

Cell-phone 

sample

Combined 

sample

Estimated eligible households (HHs) . . . . . . . . . . . . . . . . . . . . . . 135,170 42,358 177,527

Observed eligible HHs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105,481 19,827 125,308

Estimated eligible HHs from unresolved . . . . . . . . . . . . . . . . . 29,235 19,236 48,470

Estimated eligible HHs from unscreened . . . . . . . . . . . . . . . . 454 3,295 3,749

Completed HH interviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45,750 11,080 56,830

CASRO1

 HH response rate (percent) . . . . . . . . . . . . . . . . . . . . . 33.8 26.2 32.0

1

Council of American Survey Research Organizations.

Table 35. Key indicators for National Immunization Survey–Kindergarten: 2013, excluding 

U.S. territories

Key indicators Landline sample Cell-phone sample Combined sample

Estimated eligible households (HHs) . . . . . . . . . . . 1,142 6,871 8,013

Observed eligible HHs . . . . . . . . . . . . . . . . . . . . 820 2,698 3,518

Estimated eligible HHs from unresolved . . . . . . . 197 3,124 3,321

Estimated eligible HHs from unscreened . . . . . . 125 1,048 1,174

Completed HH interviews . . . . . . . . . . . . . . . . . . . 580 1,768 2,348

CASRO1

 HH response rate (percent) . . . . . . . . . . 50.8 25.7 29.3

1

Council of American Survey Research Organizations.
Series 1, No. 61  Page 83 

Table 36. Key indicators for National Immunization Survey–Flu Child Influenza Module at end of influenza season: 2010–2014, excluding 

U.S. territories

Influenza season Key indicators Landline sample Cell-phone sample Combined sample

9/1/2011–6/30/2012 Estimated eligible households (HHs) . . . . . . . . . . . . . . . . . . . . . . . . . . 40,253 189,011 229,264

Observed eligible HHs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25,242 53,020 78,262

Estimated eligible HHs from unresolved . . . . . . . . . . . . . . . . . . . . . . 7,149 97,041 104,190

Estimated eligible HHs from unscreened . . . . . . . . . . . . . . . . . . . . . 7,862 38,950 46,812

Completed HH interviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22,459 49,930 72,389

CASRO1

 HH response rate (percent) . . . . . . . . . . . . . . . . . . . . . . . . . 55.8 26.4 31.6

9/1/2012–6/30/2013 Estimated eligible HHs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43,138 652,485 695,623

Observed eligible HHs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28,044 199,785 227,829

Estimated eligible HHs from unresolved . . . . . . . . . . . . . . . . . . . . . . 7,840 376,693 384,533

Estimated eligible HHs from unscreened . . . . . . . . . . . . . . . . . . . . . 7,254 76,007 83,261

Completed HH interviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24,078 165,930 190,008

CASRO1

 HH response rate (percent) . . . . . . . . . . . . . . . . . . . . . . . . . 55.8 25.4 27.3

10/1/2013–6/30/2014 Estimated eligible HHs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60,423 138,575 198,998

Observed eligible HHs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41,934 55,900 97,834

Estimated eligible HHs from unresolved . . . . . . . . . . . . . . . . . . . . . . 11,251 59,047 70,297

Estimated eligible HHs from unscreened . . . . . . . . . . . . . . . . . . . . . 7,238 23,628 30,866

Completed HH interviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35,393 44,413 79,805

CASRO1

 HH response rate (percent) . . . . . . . . . . . . . . . . . . . . . . . . . 58.6 32.0 40.1

10/1/2014–6/30/2015 Estimated eligible HHs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38,775 124,472 163,247

Observed eligible HHs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26,754 50,855 77,609

Estimated eligible HHs from unresolved . . . . . . . . . . . . . . . . . . . . . . 7,336 53,087 60,424

Estimated eligible HHs from unscreened . . . . . . . . . . . . . . . . . . . . . 4,684 20,530 25,215

Completed HH interviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21,660 42,713 64,373

CASRO1

 HH response rate (percent) . . . . . . . . . . . . . . . . . . . . . . . . . 55.9 34.3 39.4

1

Council of American Survey Research Organizations.
Recommended Immunization Schedules for Persons Aged 0 Through 18 Y

UNITED STATES, 2014 

This schedule includes recommendations in effect as of January 1, 2014. Any dose not administered at the recommended age should be administered at a subsequent visit, when indicated and feasible. The use of a combination vaccine generally is preferred over separate injections of its equivalent component vaccines. Vaccination providers should consult the relevant Advisory Committee on Immunization Practices (ACIP) statfor detailed recommendations, available online at http://www.cdc.gov/vaccines/hcp/acip-recs/index.html. Clsignificant adverse events that follow vaccination should be reported to the Vaccine Adverse Event Reporting System (VAERS) online (http://www.vaers.hhs.gov) or by telephone (800-822-7967). 

The Recommended Immunization Schedules for 

Persons Aged 0 Through 18 Years are approved by the 

Advisory Committee on Immunization Practices 

(http://www.cdc.gov/vaccines/acip) 

American Academy of Pediatrics 

(http://www.aap.org) 

American Academy of Family Physicians 

(http://www.aafp.org) 

American College of Obstetricians and Gynecologists 

(http://www.acog.org) 

U.S. Department of Health and Human Services Centers for Disease Control and Prevention 
Series 1, No. 61  Page 85 

Not routinely 

recommended 

Vaccine Birth 

1st dose 

1 mo 

2nd dose 

2 mos 4 mos 6 mos 9 mos 12 mos 

3rd dose 

15 mos 18 mos 19–23 

mos 2-3 yrs 4-6 yrs 7-10 yrs 11-12 yrs 13–15 yrs 16–18 yrs 

Rotavirus2 (RV) RV1 (2-dose 

series); RV5 (3-dose series) Hepatitis B1 (HepB) 

1st dose 2nd dose See footnote 2 

Diphtheria, tetanus, & acellular pertussis3 (DTaP: <7 yrs) 1st dose 2nd dose 3rd dose 4th dose 5th dose 

Tetanus, diphtheria, & acellular pertussis4 (Tdap: >7 yrs) (Tdap) 

Haemophilus influenzae type 

b5 (Hib) 1st dose 2nd dose See footnote 5 3rd or 4 th dose, See foot note 5 

Pneumococcal conjugate6 

(PCV13) 1st dose 2nd dose 3rd dose 4th dose Pneumococcal polysaccharide6 (PPSV23) 

Inactivated poliovirus7 (IPV) 

(<18 yrs) 1st dose 2nd dose 3rd dose 4th dose 

Influenza8 (IIV; LAIV) 2 doses 

for some: See footnote 8 Annual vaccination (IIV only) Annual vaccination (IIV or LAIV) 

Measles, mumps, rubella9 

(MMR) 1st dose 2nd dose Varicella10 (VAR) 1st dose 2nd dose 

Hepatitis A11 (HepA) 2- dose series, See footnote 11 

Human papillomavirus12 

(HPV2: females only; HPV4: males and females) 

(3-dose 

series) 

Meningococcal1 3 (Hib-MenCY > 6 weeks; MenACWY-D 

>9 mos; MenACWY-CRM 

≥ 2 mos) 

See footnote 13 1st dose Booster 

Range of 

recommended ages for 

all children 

Range of recommended ages for catch-up 

immunization 

Range of recommended 

ages for certain high-risk 

groups 

Range of recommended ages 

during which catch-up is 

encouraged and for certain high-risk groups 

Figure 1. Recommended immunization schedule for persons aged 0 through 18 years – United States, 2014. (FOR THOSE WHO FALL BEHIND OR START LATE, SEE THE CATCH-UP SCHEDULE [FIGURE 2]). These recommendations must be read with the footnotes that follow. For those who fall behind or start late, provide catch-up vaccination at the earliest opportunity as indicated by the green bars in Figure 1. To determine minimum intervals between doses, see the catch-up schedule (Figure 2). School entry and adolescent vaccine age groups are in bold. This schedule includes recommendations in effect as of January 1, 2014. Any dose not administered at the recommended age should be administered at a subsequent visit, when indicated and feasible. The use of a combination 

vaccine generally is preferred over separate injections of its equivalent component vaccines. Vaccination providers should consult the relevant Advisory Committee on Immunization Practices (ACIP) statement for detailed 

recommendations, available online at http://www.cdc.gov/vaccines/hcp/acip-recs/index.html. Clinically significant adverse events that follow vaccination should be reported to the Vaccine Adverse Event Reporting System (VAERS) online (http://www.vaers.hhs.gov) or by telephone (800-822-7967).Suspected cases of vaccine-preventable diseases should be reported to the state or local health department. Additional information, including precautions and contraindications for vaccination, is available from CDC online (http://www.cdc.gov/vaccines/recs/vac-admin/contraindications.htm) or by telephone (800-CDC-INFO [800-232-4636]). This schedule is approved by the Advisory Committee on Immunization Practices (http//www.cdc.gov/vaccines/acip), the American Academy of Pediatrics (http://www.aap.org), the American Academy of Family Physicians (http://www.aafp.org), and the American College of Obstetricians and Gynecologists (http://www.acog.org). NOTE: The above recommendations must be read along with the footnotes of this schedule. 
FIGURE 2. Catch-up immunization schedule for persons aged 4 months through 18 years who start late or who are more than 1 month behind —United States, 2014. The figure below provides catch-up schedules and minimum intervals between doses for children whose vaccinations have been delayed. A vaccine series does not need to be re

that has elapsed between doses. Use the section appropriate for the child’s age. Always use this table in conjunction with Figure 1 and the footnotes that follow. Persons aged 4 months through 6 years Vaccine Minimum Age for Dose 1 Minimum Interval Between Doses Dose 1 to dose 2 Dose 2 to dose 3 Dose 3 to dose 4 

Hepatitis B1 Birth 4 weeks 8 weeks and at least 16 weeks after first dose; minimum age for the final dose is 24 weeks Rotavirus2 6 weeks 4 weeks 4 weeks2 

Diphtheria, tetanus, & 

acellular pertussis 3 6 weeks 4 weeks 4 weeks 6 months 

Haemophilus

influenzae type b5 6 weeks 

4 weeks if first dose administered at younger than age

12 months 

8 weeks (as final dose)

if first dose administered at age 12 through 14 months

No further doses needed 

if first dose administered at age 15 months or older 

4 weeks5 if current age is younger than 12 months and first

dose administered at < 7 months old 

8 weeks and age 12 months through 59 months (as final

dose)5 if current age is younger than 12 months and first dose

administered between 7 through 11 months (regardless of Hib 

vaccine [PRP-T or PRP-OMP] used for first dose); OR 

if current age is 12 through 59 months and first dose 

administered at younger than age 12 months; OR 

first 2 doses were PRP-OMP and administered at younger than 

12 months. 

No further doses needed if previous dose administered at age

15 months or older 

8 weeks (as final dose)

This dose only necessary for children age

59 months who received 3 (PRP-T) doses 

12 months and started the primary series 

7 months 

Pneumococcal6 6 weeks 

4 weeks if first dose administered at younger than age

12 months 

8 weeks (as final dose for healthy children) if first dose 

administered at age 12 months or older

No further doses needed for healthy children if first dose

administered at age 24 months or older 

4 weeks if current age is younger than 12 months

8 weeks (as final dose for healthy children) if current age is 12

months or older 

No further doses needed for healthy children if previous dose

administered at age 24 months or older 

8 weeks (as final dose)

This dose only necessary for children age

59 months who received 3 doses befo

months or for children at high risk who r

doses at any age 

Inactivated poliovirus7 6 weeks 4 weeks7 4 weeks7 6 months7 minimum age 4 years for fi

Meningococcal13 6 weeks 8 weeks13 See footnote 13 See footnote 13 

Measles, mumps,

rubella9 

12 

months 4 weeks 

Varicella10 12 months 3 months 

Hepatitis A11 12 months 6 months 

Persons aged 7 through 18 years 

Tetanus, diphtheria; tetanus, diphtheria, &acellular pertussis4 7 years4 4 weeks 

4 weeks if first dose of DTaP/DT administered at younger than 

age 12 months

6 months if first dose of DTaP/DT administered at age 12 

months or older and then no further doses needed for catch-up 

6 months if first dose of DTaP/DT admin

younger than age 12 months 

Human papillomavirus12 9 years Routine dosing intervals are recommended12 

Hepatitis A11 12 months 6 months 

Hepatitis B1 Birth 4 weeks 8 weeks (and at least 16 weeks after first dose) 

Inactivated poliovirus7 6 weeks 4 weeks 4 weeks7 6 months7 

Meningococcal13 6 weeks 8 weeks13 

Measles, mumps,

rubella9 12 months 4 weeks 

Varicella10 12 months 3 months if person is younger than age 13 years 4 weeks if person is aged 13 years or older 

NOTE: The above recommendations must be read along with the footnotes of this schedule. 
1. Hepatitis B (HepB) vaccine. (Minimum age: birth) 

Routine vaccination:

At birth: 

2. Rotavirus (RV) vaccines. (Minimum age: 6 weeks for both RV1 [Rotarix] and RV5 [RotaTeq]) 

Routine vaccination: 

Administer a series of RV vaccine to all infants as follo

ws: 

-- 

F

ootnotes — Recommended immunization schedule for persons aged 0 through 18 years—United Sta

For further guidance on the use of the vaccines mentioned belo

w, see: http://w

w

w.cdc.gov/vaccines/hcp/acip-recs/index.html. 

For vaccine recommendations for persons 19 years of age and older, see the adult immunization schedule. 

Additional information 

• For contraindications and precautions to use of a vaccine and for additional information regarding that vaccine, vaccination providers should consult the relevant AC

at http://w

w

w.cdc.gov/vaccines/hcp/acip-recs/index.html. 

• For purposes of calculating intervals bet

ween doses, 4 weeks = 28 days. Intervals of 4 months or greater are determined by calendar months. 

• Vaccine doses administered 4 days or less before the minimum interval are considered valid. Doses of any vaccine administered ≥5 days earlier than the minimum in

should not be counted as valid doses and should be repeated as age-appropriate. The repeat dose should be spaced after the invalid dose by the recommended mindetails, see MMWR, General Recommendations on Immunization and Reports / Vol. 60 / No. 2; Table 1. Recommended and minimum ages and intervals bet

ween vaccine d

http://w

w

w.cdc.gov/mmwr/pdf/rr/rr6002.pdf. 

• Information on travel vaccine requirements and recommendations is available at http://w

wwnc.cdc.gov/travel/destinations/list. 

• For vaccination of persons with primary and secondary immunodeficiencies, see Table 13, “Vaccination of persons with primary and secondary immunodeficiencies,” in G

on Immunization (ACIP), available at http://w

w

w.cdc.gov/mmwr/pdf/rr/rr6002.pdf.; and American Academy of Pediatrics. Immunization in Special Clinical Circumstan

Kimberlin DW, Long SS eds. Red Book: 2012 report of the Committee on Infectious Diseases. 29th ed. Elk Grove Village, IL: American Academy of Pediatrics. 

3. 

• Administer monovalent HepB vaccine to all newborns before hospital discharge. • For infants born to hepatitis B surface antigen (HBsAg)-positive mothers, administer HepB vaccine and 

0.5 mL of hepatitis B immune globulin (HBIG) within 12 hours of birth. These infants should be tested 

for HBsAg and antibody to HBsAg (anti-HBs) 1 to 2 months after completion of the HepB series, at age 

9 through 18 months (preferably at the next well-child visit). 

• If mother’s HBsAg status is unknown, within 12 hours of birth administer HepB vaccine regardless of 

birth weight. For infants weighing less than 2,000 grams, administer HBIG in addition to HepB vaccine within 12 hours of birth. Determine mother’s HBsAg status as soon as possible and, if mother is HBsAgpositive, also administer HBIG for infants weighing 2,000 grams or more as soon as possible, but no later than age 7 days. 

4. 

Doses following the birth dose: • The second dose should be administered at age 1 or 2 months. Monovalent HepB vaccine should be 

used for doses administered before age 6 weeks. 

• Infants who did not receive a birth dose should receive 3 doses of a HepB-containing vaccine on a 

schedule of 0, 1 to 2 months, and 6 months starting as soon as feasible. See Figure 2. 

• Administer the second dose 1 to 2 months after the first dose (minimum interval of 4 weeks), 

administer the third dose at least 8 weeks after the second dose AND at least 16 weeks after the first dose. The final (third or fourth) dose in the HepB vaccine series should be administered no earlier than age 24 weeks. 

• Administration of a total of 4 doses of HepB vaccine is permitted when a combination vaccine 

containing HepB is administered after the birth dose. 

Catch-up vaccination: 

• Unvaccinated persons should complete a 3-dose series. • A 2-dose series (doses separated by at least 4 months) of adult formulation Recombivax HB is licensed 

for use in children aged 11 through 15 years. 

• For other catch-up guidance, see Figure 2. 

5. 

1. If Rotarix is used, administer a 2-dose series at 2 and 4 months of age. 2. If RotaTeq is used, administer a 3-dose series at ages 2, 4, and 6 months. 3. If any dose in the series was RotaTeq or vaccine product is unknown for any dose in the series, a total 

of 3 doses of RV vaccine should be administered. 

Catch-up vaccination: 

• The maximum age for the first dose in the series is 14 weeks, 6 days; vaccination should not be 

initiated for infants aged 15 weeks, 0 days or older.

• The maximum age for the final dose in the series is 8 months, 0 days. • For other catch-up guidance, see Figure 2. 

Diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccineException: DTaP-IPV [Kinrix]: 4 years) Routine vaccination: • Administer a 5-dose series of DTaP vaccine at ages 2, 4, 6, 15 through 1

The fourth dose may be administered as early as age 12 months, provid

elapsed since the third dose. 

Catch-up vaccination: 

• The fifth dose of DTaP vaccine is not necessary if the fourth dose was ad• For other catch-up guidance, see Figure 2. Tetanus and diphtheria toxoids and acellular pertussis (Tdap) vaccineBoostrix, 11 years for Adacel) Routine vaccination: • Administer 1 dose of Tdap vaccine to all adolescents aged 11 through • Tdap may be administered regardless of the interval since the last tetanus and • Administer 1 dose of Tdap vaccine to pregnant adolescents during ea

27 through 36 weeks gestation) regardless of time since prior Td or Td

Catch-up vaccination: • Persons aged 7 years and older who are not fully immunized with DTa

vaccine as 1 (preferably the first) dose in the catch-up series; if additiovaccine. For children 7 through 10 years who receive a dose of Tdap a

adolescent Tdap vaccine dose at age 11 through 12 years should NOT administered instead 10 years after the Tdap dose. 

• Persons aged 11 through 18 years who have not received Tdap vaccin

by tetanus and diphtheria toxoids (Td) booster doses every 10 years t

• Inadvertent doses of DTaP vaccine: 

If administered inadvertently to a child aged 7 through 10 years m

series. This dose may count as the adolescent Tdap dose, or the chibooster dose at age 11 through 12 years. 

If administered inadvertently to an adolescent aged 11 through 18 

counted as the adolescent Tdap booster. 

• For other catch-up guidance, see Figure 2. Haemophilus influenzae type b (Hib) conjugate vaccine. (Minimum a

DTaP-IPV/Hib (Pentacel) and Hib-MenCY (MenHibrix)], PRP-OMP [Pedfor PRP-T [Hiberix]) Routine vaccination: 

• Administer a 2- or 3-dose Hib vaccine primary series and a booster do

vaccine used in primary series) at age 12 through 15 months to comp

• The primary series with ActHIB, MenHibrix, or Pentacel consists of 3 d

at 2, 4, and 6 months of age. The primary series with PedvaxHib or CO

should be administered at 2 and 4 months of age; a dose at age 6 mo

• One booster dose (dose 3 or 4 depending on vaccine used in primary 

be administered at age 12 through 15 months. An exception is Hiberbe used for the booster (final) dose in children aged 12 months throuleast 1 prior dose of Hib-containing vaccine. 
5. Haemophilus influenzae type b (Hib) conjugate vaccine (cont’d) For further guidance on the use of the vaccines mentioned belo

w, see: http://w

w

w.cdc.gov/vaccines/hcp/acip-recs/index.html. 

6. 

• For recommendations on the use of MenHibrix in patients at increased risk for meningococcal disease, 

please refer to the meningococcal vaccine footnotes and also to MMWR March 22, 2013; 62(RR02);1-22, 

available at http://w

w

w.cdc.gov/mmwr/pdf/rr/rr6202.pdf. 

Catch-up vaccination: 

• If dose 1 was administered at ages 12 through 14 months, administer a second (final) dose at least 8 

weeks after dose 1, regardless of Hib vaccine used in the primary series. 

• If the first 2 doses were PRP-OMP (PedvaxHIB or COMVAX), and were administered at age 11 months or 

younger, the third (and final) dose should be administered at age 12 through 15 months and at least 8 

weeks after the second dose. 

• If the first dose was administered at age 7 through 11 months, administer the second dose at least 4 

weeks later and a third (and final) dose at age 12 through 15 months or 8 weeks after second dose, 

whichever is later, regardless of Hib vaccine used for first dose. 

• If first dose is administered at younger than 12 months of age and second dose is given bet

ween 12 

through 14 months of age, a third (and final) dose should be given 8 weeks later. 

• For unvaccinated children aged 15 months or older, administer only 1 dose. • For other catch-up guidance, see Figure 2. For catch-up guidance related to MenHibrix, please see the 

meningococcal vaccine footnotes and also MMWR March 22, 2013; 62(RR02);1-22, available at 

http://w

w

w.cdc.gov/mmwr/pdf/rr/rr6202.pdf. 

Vaccination of persons with high-risk conditions: 

• Children aged 12 through 59 months who are at increased risk for Hib disease, including 

chemotherapy recipients and those with anatomic or functional asplenia (including sickle cell disease), human immunodeficiency virus (HIV) infection, immunoglobulin deficiency, or early component 

complement deficiency, who have received either no doses or only 1 dose of Hib vaccine before 12 

months of age, should receive 2 additional doses of Hib vaccine 8 weeks apart; children who received 2 or more doses of Hib vaccine before 12 months of age should receive 1 additional dose. 

• For patients younger than 5 years of age undergoing chemotherapy or radiation treatment who 

received a Hib vaccine dose(s) within 14 days of starting therapy or during therapy, repeat the dose(s) 

at least 3 months following therapy completion. 7. 

• Recipients of hematopoietic stem cell transplant (HSCT) should be revaccinated with a 3-dose regimen 

of Hib vaccine starting 6 to 12 months after successful transplant, regardless of vaccination history; doses should be administered at least 4 weeks apart. 

• A single dose of any Hib-containing vaccine should be administered to unimmunized* children and 

adolescents 15 months of age and older undergoing an elective splenectomy; if possible, vaccine should be administered at least 14 days before procedure. 

• Hib vaccine is not routinely recommended for patients 5 years or older. Ho

wever, 1 dose of Hib vaccine 

should be administered to unimmunized* persons aged 5 years or older who have anatomic or functional asplenia (including sickle cell disease) and unvaccinated persons 5 through 18 years of age with human immunodeficiency virus (HIV) infection. 

* Patients who have not received a primary series and booster dose or at least 1 dose of Hib vaccine 

after 14 months of age are considered unimmunized. 

6. Pneumococcal vaccines. (Minimum age: 6 weeks for PCV13, 2 years for PPSV23) 

Routine vaccination with PCV13: 

• Administer a 4-dose series of PCV13 vaccine at ages 2, 4, and 6 months and at age 12 through 15 months. 8. • For children aged 14 through 59 months who have received an age-appropriate series of 7-valent PCV 

(PCV7), administer a single supplemental dose of 13-valent PCV (PCV13). 

Catch-up vaccination with PCV13: 

• Administer 1 dose of PCV13 to all healthy children aged 24 through 59 months who are not 

completely vaccinated for their age. 

• For other catch-up guidance, see Figure 2. 

Vaccination of persons with high-risk conditions with PCV13 and PPSV23: 

• All recommended PCV13 doses should be administered prior to PPSV23 vaccination if possible. • For children 2 through 5 years of age with any of the following conditions: chronic heart disease 

(particularly cyanotic congenital heart disease and cardiac failure); chronic lung disease (including asthma if treated with high-dose oral corticosteroid therapy); diabetes mellitus; cerebrospinal fluid leak; cochlear implant; sickle cell disease and other hemoglobinopathies; anatomic or functional asplenia; HIV infection; chronic renal failure; nephrotic syndrome; diseases associated with treatment with immunosuppressive drugs or radiation therapy, including malignant neoplasms, leukemias, lymphomas, and Hodgkin disease; solid organ transplantation; or congenital immunodeficiency: 

1. Administer 1 dose of PCV13 if 3 doses of PCV (PCV7 and/or PCV13) were received previously. 2. Administer 2 doses of PCV13 at least 8 weeks apart if fewer than 3 doses of PCV (PCV7 and/or PCV13) 

were received previously. 

Pneumococcal vaccines (cont’d) 

3. Administer 1 supplemental dose of PCV13 if 4 doses of PCV7 or ot

series was received previously. 

4. The minimum interval bet

ween doses of PCV (PCV7 or PCV13) is 

5. For children with no history of PPSV23 vaccination, administer PP

recent dose of PCV13. 

• For children aged 6 through 18 years who have cerebrospinal fluid leak; 

and other hemoglobinopathies; anatomic or functional asplenia; congenHIV infection; chronic renal failure; nephrotic syndrome; diseases associaimmunosuppressive drugs or radiation therapy, including malignant neoHodgkin disease; generalized malignancy; solid organ transplantation; o

1. If neither PCV13 nor PPSV23 has been received previously, adm

dose of PPSV23 at least 8 weeks later. 

2. If PCV13 has been received previously but PPSV23 has not, adm

weeks after the most recent dose of PCV13. 

3. If PPSV23 has been received but PCV13 has not, administer 1 dos

most recent dose of PPSV23. 

• For children aged 6 through 18 years with chronic heart disease (pa

disease and cardiac failure), chronic lung disease (including asthma 

corticosteroid therapy), diabetes mellitus, alcoholism, or chronic liv

PPSV23, administer 1 dose of PPSV23. If PCV13 has been received padministered at least 8 weeks after any prior PCV13 dose. 

• A single revaccination with PPSV23 should be administered 5 years 

with sickle cell disease or other hemoglobinopathies; anatomic or for acquired immunodeficiencies; HIV infection; chronic renal failureassociated with treatment with immunosuppressive drugs or radiatneoplasms, leukemias, lymphomas, and Hodgkin disease; generaliztransplantation; or multiple myeloma. 

Inactivated poliovirus vaccine (IPV). (Minimum age: 6 weeks) Routine vaccination: 

• Administer a 4-dose series of IPV at ages 2, 4, 6 through 18 months, 

dose in the series should be administered on or after the fourth birtthe previous dose. 

Catch-up vaccination: 

• In the first 6 months of life, minimum age and minimum intervals are on

for imminent exposure to circulating poliovirus (i.e., travel to a polio-end

• If 4 or more doses are administered before age 4 years, an additiona

age 4 through 6 years and at least 6 months after the previous dose

• A fourth dose is not necessary if the third dose was administered at 

months after the previous dose. 

• If both OPV and IPV were administered as part of a series, a total of 4 dos

of the child’s current age. IPV is not routinely recommended for U.S. resid

• For other catch-up guidance, see Figure 2. 

Influenza vaccines. (Minimum age: 6 months for inactivated influenattenuated influenza vaccine [LAIV]) Routine vaccination: 

• Administer influenza vaccine annually to all children beginning at ag

nonpregnant persons aged 2 through 49 years, either LAIV or IIV may NOT be administered to some persons, including 1) those with asthmhad wheezing in the past 12 months, or 3) those who have any other predispose them to influenza complications. For all other contraindic2013; 62 (No. RR-7):1-43, available at http://www.cdc.gov/mmwr/pdf/

For children aged 6 months through 8 years: 

• For the 2013–14 season, administer 2 doses (separated by at least 4 

receiving influenza vaccine for the first time. Some children in this avaccinated previously will also need 2 doses. For additional guidanc

2013-14 ACIP influenza vaccine recommendations, MMWR 2013; 62 

http://w

w

w.cdc.gov/mmwr/pdf/rr/rr6207.pdf. 

• For the 2014–15 season, follow dosing guidelines in the 2014 ACIP 

recommendations. 

For persons aged 9 years and older: 

• Administer 1 dose. 
For further guidance on the use of the vaccines mentioned belo

w, see: http://w

w

w.cdc.gov/vaccines/hcp/acip-recs/index.html. 

9. 

Measles, mumps, and rubella (MMR) vaccine. (Minimum age: 12 months for routine vaccination) 

Routine vaccination: 

• Administer a 2-dose series of MMR vaccine at ages12 through 15 months and 4 through 6 years. The second 

dose may be administered before age 4 years, provided at least 4 weeks have elapsed since the first dose. 

• Administer 1 dose of MMR vaccine to infants aged 6 through 11 months before departure from the 

United States for international travel. These children should be revaccinated with 2 doses of MMR 

vaccine, the first at age 12 through 15 months (12 months if the child remains in an area where disease 

risk is high), and the second dose at least 4 weeks later. 

• Administer 2 doses of MMR vaccine to children aged 12 months and older before departure from the 

United States for international travel. The first dose should be administered on or after age 12 months and the second dose at least 4 weeks later. 

Catch-up vaccination: 

• Ensure that all school-aged children and adolescents have had 2 doses of MMR vaccine; the minimum 

interval bet

ween the 2 doses is 4 weeks. 

10. Varicella (VAR) vaccine. (Minimum age: 12 months) 

Routine vaccination: 

• Administer a 2-dose series of VAR vaccine at ages 12 through 15 months and 4 through 6 years. The 

second dose may be administered before age 4 years, provided at least 3 months have elapsed since the first dose. If the second dose was administered at least 4 weeks after the first dose, it can be accepted as valid. 

Catch-up vaccination: 

• Ensure that all persons aged 7 through 18 years without evidence of immunity (see MMWR 2007; 56 

[No. RR-4], available at http://w

w

w.cdc.gov/mmwr/pdf/rr/rr5604.pdf) have 2 doses of varicella vaccine. 

For children aged 7 through 12 years, the recommended minimum interval bet

ween doses is 3 months 

(if the second dose was administered at least 4 weeks after the first dose, it can be accepted as valid); 

for persons aged 13 years and older, the minimum interval bet

ween doses is 4 weeks. 

11. Hepatitis A (HepA) vaccine. (Minimum age: 12 months) 

Routine vaccination: 

• Initiate the 2-dose HepA vaccine series at 12 through 23 months; separate the 2 doses by 6 to 18 months. • Children who have received 1 dose of HepA vaccine before age 24 months should receive a second dose 

6 to 18 months after the first dose. 

• For any person aged 2 years and older who has not already received the HepA vaccine series, 2 doses of 

HepA vaccine separated by 6 to 18 months may be administered if immunity against hepatitis A virus infection is desired. 

Catch-up vaccination: 

• The minimum interval bet

ween the t

wo doses is 6 months. 

Special populations: • Administer 2 doses of HepA vaccine at least 6 months apart to previously unvaccinated persons who 

live in areas where vaccination programs target older children, or who are at increased risk for infection. 

This includes persons traveling to or working in countries that have high or intermediate endemicity of 

infection; men having sex with men; users of injection and non-injection illicit drugs; persons who work with HAV-infected primates or with HAV in a research laboratory; persons with clotting-factor disorders; persons with chronic liver disease; and persons who anticipate close, personal contact (e.g., household or regular babysitting) with an international adoptee during the first 60 days after arrival in the United 

States from a country with high or intermediate endemicity. The first dose should be administered as 

soon as the adoption is planned, ideally 2 or more weeks before the arrival of the adoptee. 

12. Human papillomavirus (HPV) vaccines. (Minimum age: 9 years for HPV2 [Cervarix] and HPV4 

[Gardasil]) 

Routine vaccination: 

• Administer a 3-dose series of HPV vaccine on a schedule of 0, 1-2, and 6 months to all adolescents aged 11 

through 12 years. Either HPV4 or HPV2 may be used for females, and only HPV4 may be used for males. 

• The vaccine series may be started at age 9 years. • Administer the second dose 1 to 2 months after the first dose (minimum interval of 4 weeks), 

administer the third dose 24 weeks after the first dose and 16 weeks after the second dose (minimum interval of 12 weeks). 

Catch-up vaccination: 

• Administer the vaccine series to females (either HPV2 or HPV4) and males (HPV4) at age 13 through 18 

years if not previously vaccinated. 

• Use recommended routine dosing intervals (see above) for vaccine series catch-up. 

13. 

Meningococcal conjugate vaccines. (Minimum age: 6 weeks for Hib-MenACWY-D [Menactra], 2 months for MenACWY-CRM [Menveo]) Routine vaccination: 

• Administer a single dose of Menactra or Menveo vaccine at age 11 t

dose at age 16 years. 

• Adolescents aged 11 through 18 years with human immunodeficie

receive a 2-dose primary series of Menactra or Menveo with at least 

• For children aged 2 months through 18 years with high-risk conditi

Catch-up vaccination: 

• Administer Menactra or Menveo vaccine at age 13 through 18 years • If the first dose is administered at age 13 through 15 years, a booste

age 16 through 18 years with a minimum interval of at least 8 week

• If the first dose is administered at age 16 years or older, a booster do• For other catch-up guidance, see Figure 2. 

Vaccination of persons with high-risk conditions and other perso

• Children with anatomic or functional asplenia (including sickle cell 

1. For children younger than 19 months of age, administer a 4-dose i

at 2, 4, 6, and 12 through 15 months of age. 

2. For children aged 19 through 23 months who have not complet

administer 2 primary doses of Menveo at least 3 months apart. 

3. For children aged 24 months and older who have not received 

Menveo or Menactra, administer 2 primary doses of either Menact

If Menactra is administered to a child with asplenia (including si

Menactra until 2 years of age and at least 4 weeks after the comp

• Children with persistent complement component deficiency: 

1. For children younger than 19 months of age, administer a 4-dose 

Menveo at 2, 4, 6, and 12 through 15 months of age. 

2. For children 7 through 23 months who have not initiated vaccin

on age and vaccine brand: a. For children who initiate vaccination with Menveo at 7 months 

series should be administered with the second dose after 12 mafter the first dose. 

b. For children who initiate vaccination with Menactra at 9 months 

series of Menactra should be administered at least 3 months a

c. For children aged 24 months and older who have not receiv

Menveo, or Menactra, administer 2 primary doses of either 

Me

apart. 

• For children who travel to or reside in countries in which meningoc

or epidemic, including countries in the African meningitis belt or thappropriate formulation and series of Menactra or Menveo for protW meningococcal disease. Prior receipt of MenHibrix is not sufficienmeningitis belt or the Hajj because it does not contain serogroups A 

• For children at risk during a community outbreak attributable to a v

complete an age- and formulation-appropriate series of MenHibrix, 

• For booster doses among persons with high-risk conditions, refer to 

available at http://w

w

w.cdc.gov/mmwr/preview/mmwrhtml/rr6202

Catch-up recommendations for persons with high-risk condition

1. If MenHibrix is administered to achieve protection against meni

appropriate series of MenHibrix should be administered. 

2. If the first dose of MenHibrix is given at or after 12 months of age, 

least 8 weeks apart to ensure protection against serogroups C an

3. For children who initiate vaccination with Menveo at 7 months 

series should be administered with the second dose after 12 mafter the first dose. 

4. For other catch-up recommendations for these persons, refer to M

at http://w

w

w.cdc.gov/mmwr/preview/mmwrhtml/rr6202a1.htm

For complete information on use of meningococcal vaccines, inc

vaccination of persons at increased risk of infection, see MMWR Mavailable at http://w

w

w.cdc.gov/mmwr/pdf/rr/rr6202.pdf.
Page 90  Series 1, No. 61

Appendix II. Definitions of Terms 

3:3:1—The vaccine series of 3 or 

more DTaP/DTP/DT doses, 3 or more 

polio doses, and 1 or more MMR doses.

4:3:1—The vaccine series of 4 or 

more DTaP/DTP/DT doses, 3 or more 

polio doses, and 1 or more MMR doses.

4:3:1:3—The vaccine series of 4 or 

more DTaP/DTP/DT doses, 3 or more 

polio doses, 1 or more MMR doses, and 3 

or more Hib doses of any type.

4:3:1:H (routine Hib)—The vaccine 

series of 4 or more DTaP/DTP/DT doses, 

3 or more polio doses, 1 or more MMR 

doses, and 4 or more doses of Hib of any 

type or 2 doses of Hib of Merck types 

followed by 1 or more doses of Hib of 

any type (routine recommendation).

4:3:1:H (shortage Hib)—The 

vaccine series of 4 or more DTaP/DTP/

DT doses, 3 or more polio doses, 1 

or more MMR doses, and 3 or more 

doses of Hib of any type or 2 or more 

doses of Hib of Merck types (shortage 

recommendation).

4:3:1:3:3—The vaccine series of 4 

or more DTaP/DTP/DT doses, 3 or more 

polio doses, 1 or more MMR doses, 3 

or more Hib doses of any type, and 3 or 

more HepB doses.

4:3:1:H:3 (routine Hib)—The 

vaccine series of 4 or more DTaP/DTP/

DT doses, 3 or more polio doses, 1 or 

more MMR doses, 4 or more doses of 

Hib of any type or 2 doses of Hib of 

Merck types followed by 1 or more 

doses of Hib of any type (routine 

recommendation), and 3 or more HepB 

doses.

4:3:1:H:3 (shortage Hib)—The 

vaccine series of 4 or more DTaP/

DTP/DT doses, 3 or more polio doses, 

1 or more MMR doses, 3 or more 

doses of Hib of any type or 2 or more 

doses of Hib of Merck types (shortage 

recommendation), and 3 or more HepB 

doses.

4:3:1:3:3:1—The vaccine series of 4 

or more DTaP/DTP/DT doses, 3 or more 

polio doses, 1 or more MMR doses, 3 or 

more Hib doses of any type, 3 or more 

HepB doses, and 1 or more varicella 

doses given at age 12 months and over.

4:3:1:H:3:1 (routine Hib)—The 

vaccine series of 4 or more DTaP/DTP/

DT doses, 3 or more polio doses, 1 or 

more MMR doses, 4 or more doses of 

Hib of any type or 2 doses of Hib of 

Merck types followed by 1 or more 

doses of Hib of any type (routine 

recommendation), 3 or more HepB doses, 

and 1 or more varicella doses given at 

age 12 months or over.

4:3:1:H:3:1 (shortage Hib)—The 

vaccine series of 4 or more DTaP/

DTP/DT doses, 3 or more polio doses, 

1 or more MMR doses, 3 or more 

doses of Hib of any type or 2 or more 

doses of Hib of Merck types (shortage 

recommendation), 3 or more HepB doses, 

and 1 or more varicella doses given at 

age 12 months and over.

4:3:1:3:3:1:3—The vaccine series 

of 4 or more DTaP/DTP/DT doses, 3 or 

more polio doses, 1 or more MMR doses, 

3 or more Hib doses of any type, 3 or 

more HepB doses, 1 or more varicella 

doses given at age 12 months and over, 

and 3 or more PCV doses.

4:3:1:H:3:1:3 (routine Hib)—The 

vaccine series of 4 or more DTaP/DTP/

DT doses, 3 or more polio doses, 1 or 

more MMR doses, 4 or more doses of 

Hib of any type or 2 doses of Hib of 

Merck types followed by 1 or more 

doses of Hib of any type (routine 

recommendation), 3 or more HepB doses, 

1 or more varicella doses given at age 

12 months and over, and 3 or more PCV 

doses.

4:3:1:H:3:1:3 (shortage Hib)—

The vaccine series of 4 or more DTaP/

DTP/DT doses, 3 or more polio doses, 

1 or more MMR doses, 3 or more 

doses of Hib of any type or 2 or more 

doses of Hib of Merck types (shortage 

recommendation), 3 or more HepB doses, 

1 or more varicella doses given at age 

12 months and over, and 3 or more PCV 

doses.

4:3:1:3:3:1:4—The vaccine series 

of 4 or more DTaP/DTP/DT doses, 3 or 

more polio doses, 1 or more MMR doses, 

3 or more Hib doses, 3 or more HepB 

doses of any type, 1 or more varicella 

doses given at age 12 months and over, 

and 4 or more PCV doses.

4:3:1:H:3:1:4 (routine Hib)—The 

vaccine series of 4 or more DTaP/DTP/

DT doses, 3 or more polio doses, 1 or 

more MMR doses, 4 or more doses of 

Hib of any type or 2 doses of Hib of 

Merck types followed by 1 or more 

doses of Hib of any type (routine 

recommendation), 3 or more HepB doses, 

1 or more varicella doses given at age 

12 months and over, and 4 or more PCV 

doses.

4:3:1:H:3:1:4 (shortage Hib)—

The vaccine series of 4 or more DTaP/

DTP/DT doses, 3 or more polio doses, 

1 or more MMR doses, 3 or more 

doses of Hib of any type or 2 or more 

doses of Hib of Merck types (shortage 

recommendation), 3 or more HepB doses, 

1 or more varicella doses given at age 

12 months and over, and 4 or more PCV 

doses.

Accurint—A company that maintains 

a database of public records and can 

conduct custom batch searches that 

determine the names and addresses of 

individuals associated with known phone 

numbers or vice versa.

Address-based sampling (ABS)—A 

method of probability sampling in which 

addresses are selected or derived from the 

U.S. Postal Service's Delivery Sequence 

File. The file is used primarily for surveys 

of households and people.

Adequate provider data—For the 

purposes of the National Immunization 

Survey, the idea that the information 

received from the child's providers is 

sufficient to determine whether the 

child is up to date (UTD) with the 

recommended vaccination schedule.

From 2005 through 2011, children 

aged 19–35 months with adequate 

provider data included those children 

for whom consent to contact providers 

was received and either (1) all identified 

vaccination providers returned the 

immunization history questionnaire 

(IHQ) or medical records or (2) some 

but not all of the identified vaccination 

providers returned the IHQ or medical 

records, at least one of these vaccination 

reports was received, and at least one of 
Series 1, No. 61  Page 91 

the following additional criteria apply: 

a) the responding provider(s) reported 

the child as UTD with recommended 

doses of vaccines in the 4:3:1:3 series; b) 

the child was UTD for the 4:3:1:3 series 

when vaccinations given after the date of 

the household interview were counted; 

c) the responding provider(s) reported at 

least one measles-containing vaccination; 

or d) the responding provider(s) reported 

at least as many doses of the key 

recommended vaccines as the household 

respondent.

Beginning in 2012, the household 

questionnaire was shortened, eliminating 

the household report of vaccinations 

the children received, and the criteria 

for adequate provider data status was 

changed to include children for whom 

consent to contact providers was received 

and at least one provider returned the 

IHQ or medical records containing 

a history of at least one received 

vaccination. Since 2005, “zero-shot 

children” are considered to have adequate 

provider data; see definition.

Adolescent—Person aged 13–17 

years.

American Community Survey—An 

ongoing statistical survey conducted 

by the U.S. Census Bureau that is sent 

to approximately 250,000 addresses 

monthly (or 3 million per year). It 

regularly gathers information previously 

collected in the now-defunct long form of 

the decennial census.

Area probability sample—A sample 

in which geographic areas are sampled 

with known probabilities. While an 

area probability sample design could 

conceivably provide for selecting areas 

that are themselves the units being 

studied, in survey research, an area 

probability sample is usually one in 

which areas are selected as part of a 

clustered or multistage design.

ASCII—American Standard Code for 

Information Interchange is an Englishlanguage text format for character 

encoding.

Attenuation estimator—Dual-frame 

estimator that combines the separate 

estimators from the landline sample and 

the cell-phone sample by minimizing the 

mean squared error for a specific vaccine 

of interest. The attenuation estimator is 

biased, except when landline and cellphone-only (CPO) children are similarly 

vaccinated, but it has a smaller mean 

squared error compared with the unbiased 

estimator. 

Typically, when an attenuation 

estimator is used for the National 

Immunization Survey, the CPO sample 

size is relatively small, in fact, too small 

to encourage use of a direct samplebased estimator. Instead, the mean of the 

CPO domain is estimated by a weighted 

average of the means of the CPO sample 

and the landline sample (either the 

entire landline sample or the proxy CPO 

sample). Direct sample-based estimators 

are used for the landline-only and dualuser domains.

Balanced dual user—Household that 

has both landline and wireless telephone 

service, and receives an approximately 

equal amount of calls from either the 

landline or the cell phone. A household 

is classified as a balanced dual-user 

household if the respondent answered, 

“some received on cell phones and some 

received on regular phones,” to the 

survey question, "Of all the telephone 

calls that you and your family receive, 

are nearly all received on cell phones, 

nearly all received on regular phones, or 

some received on cell phones and some 

received on regular phones?" 

Bottom coding—The suppression of 

extremely low values by resetting these 

values to be equal to a predetermined 

minimum lower bound. This method is 

used to protect confidentiality and reduce 

disclosure risk of respondents with 

unique sociodemographic characteristics. 

For example, income-to-poverty ratio is 

bottom-coded to 0.5.

Cell-phone-mainly—A household 

that has both landline and wireless 

telephone service, but the respondent 

states that household residents are “not 

likely at all” or are “somewhat unlikely” 

to answer the landline phone if it rang. 

Households determined to be cell-phonemainly selected one of these answers 

in response to the survey question, 

"Thinking just about the landline home 

phone, not your cell phone, if that 

telephone rang and someone were home, 

under normal circumstances how likely is 

it that it would be answered?” 

Cell-phone-mostly—A household 

that has both landline and wireless 

telephone service, but reports that a 

few of their calls are received on their 

landline phone and most are received on 

their cell phone. Households classified 

as cell-phone-mostly answered, “all or 

almost all calls received on cell phones” 

in response to the survey question, "Of 

all the telephone calls that you and your 

family receive, are nearly all received on 

cell phones, nearly all received on regular 

phones, or some received on cell phones 

and some received on regular phones?"

Cell-phone-only—A household that 

only has wireless telephone service. A 

household was classified as cell-phoneonly if respondents answered “no” to the 

survey question, "Do you have a landline 

telephone in your household?" 

Census region—Groupings of states 

that subdivide the United States for 

the presentation of data. There are four 

census regions: Northeast, Midwest, 

South, and West. Each of the four census 

regions is divided into two or more 

census divisions.

Central city—The largest place in 

each metropolitan statistical area and 

consolidated metropolitan statistical 

area. In some cases, additional places 

are designated as central cities. A few 

primary metropolitan statistical areas 

do not have central cities. The largest 

central city, and in some cases, up to two 

additional central cities, are included in 

the metropolitan area (MA); there also 

are central cities that are not included 

in an MA. An MA central city does not 

include any part of a place that extends 

outside the MA boundary.

Child-level analytic file —A 

4-quarter, child-level SAS data set 

with one record for each National 

Immunization Survey-eligible child 

for whom Section C of the household 

interview was completed. It contains all 

variables from the household interview 

and the provider record check, in addition 

to composite, geographic, and weighting 

variables.

Composite adjustment factor—A 

factor applied when integrating the 

landline-sample and cell-phone-sample 

estimated totals for the dual-user 

telephone domain, intended to yield a 
Page 92  Series 1, No. 61

combined estimate for the domain that 

achieves minimum mean squared error.

Computer-assisted telephone 

interviewing (CATI)—A telephone 

surveying technique in which the 

interviewer follows a script provided by 

a software application. It is a structured 

system of microdata collection by 

telephone that speeds up the collection 

and editing of microdata and permits the 

interviewer to educate the respondents 

on the importance of timely and accurate 

data. The software is able to customize 

the flow of the questionnaire based on the 

answers provided, as well as information 

already known about the participant.

Current Population Survey—The 

primary source of labor force statistics 

for the U.S. population. This survey 

is a source of numerous high-profile 

economic statistics, including the national 

unemployment rate, and it provides data 

on a wide range of issues relating to 

employment and earnings. It is sponsored 

jointly by the U.S. Census Bureau and the 

U.S. Bureau of Labor Statistics.

Delivery sequence file—A 

computerized file that contains all 

delivery point addresses serviced by the 

U.S. Postal Service, with the exception of 

general delivery.

DTaP—Diphtheria and tetanus 

toxoids and acellular pertussis vaccine.

DTP—Diphtheria and tetanus toxoids 

and pertussis vaccine.

DT—Diphtheria and tetanus toxoids 

vaccine.

Dual-frame sampling design—

Refers to the utilization of two separate 

potentially overlapping sample frames 

to interview a population of interest. 

The most common dual-frame sampling 

design in use currently uses landline and 

cell phone random-digit-dialing telephone 

numbers to reach a representative sample 

of households.

Dual users—A household that has 

both landline and wireless telephone 

service. Dual users include landline 

mostly, balanced dual users, and cellphone mostly. 

For households sampled from the 

landline frame, households are classified 

as dual user if a respondent answered 

at least one to the survey question, "In 

total, how many working cell phones 

do you and your household members 

have available for personal use? Please 

don’t count cell phones that are used 

exclusively for business purposes." 

For cases drawn from the cell-phone 

frame, the household is determined to 

be dual user if a respondent answered at 

least one to the survey question, "How 

many landline telephone numbers are 

residential numbers?" 

Effective completed interviews—The 

number of completed interviews, adjusted 

for the effects of sample design and 

sample weighting on the variance of key 

survey estimates.

Estimation area—Geographic areas 

for which the National Immunization 

Survey produces vaccination 

estimates. There are 56 core estimation 

areas consisting of 50 states and 6 

immunization grantee (or cooperative 

agreement awardee) areas comprising 

selected large urban areas, namely 

Chicago, Ill.; Houston, Tex.; New York, 

N.Y.; Philadelphia, Pa.; San Antonio, 

Tex.; and Washington, D.C. In addition 

to the core areas, additional areas become 

estimation areas depending on available 

funding.

Flu—Influenza.

H1N1 flu—H1N1, sometimes called 

“swine flu,” is an influenza virus first 

detected in people in the United States in 

April 2009. This person-to-person virus 

spread worldwide, in much the same way 

that regular seasonal influenza viruses 

spread. In June 2009, the World Health 

Organization declared that a pandemic of 

H1N1 flu was underway.

Health Insurance Module—A section 

in the National Immunization Survey that 

asks questions about the extent and type 

of health insurance coverage the child has 

had since birth. 

HepA—Hepatitis A.

HepB—Hepatitis B.

Hib—Haemophilus influenzae type b 

vaccine.

Hib routine recommendation—Four 

or more doses of Hib of any type or two 

or more doses of Hib of Merck types, 

followed by one dose of Hib of any type.

Hib shortage recommendation—

Three or more doses of Hib of any type 

or two or more doses of Hib of Merck 

types.

HIPAA—The Health Insurance 

Portability and Accountability Act 

of 1996 provides health insurance 

protections for people and establishes 

security and privacy standards for the use 

of electronic health records and personal 

identifiers.

HPV—Human papillomavirus.

Immunization action plan—

State-based programs sponsored by 

the Centers for Disease Control and 

Prevention in order to increase the rate of 

immunizations among young children.

Immunization history 

questionnaire—The questionnaire sent 

to the immunization provider(s) of a 

National Immunization Survey-sampled 

child to gather the child’s immunization 

history, and information about the 

provider's facility for the provider 

record check phase of the National 

Immunization Survey.

Immunization information 

systems—Confidential, population-based, 

computerized databases that record 

all immunization doses administered 

by participating providers to persons 

residing within a given geopolitical area.

Item nonresponse—A missing 

response to a particular questionnaire 

item, whether by interview breakoff or by 

a “don’t know” or “refused” response.

Landline-mostly—A household that 

has both landline and wireless telephone 

service, but reports that all or most of 

their calls are received on their landline 

telephone. A household is classified 

as a landline-mostly if the respondent 

answers “all or almost all calls received 

on regular phones” in response to the 

survey question, "Of all the telephone 

calls that you and your family receive, 

are nearly all received on cell phones, 

nearly all received on regular phones, or 

some received on cell phones and some 

received on regular phones?"

Landline only—A household that 

only has landline telephone service. 

Households sampled from the landline 

frame that answered "None" to the survey 

question, "In total, how many working 

cell phones do you and your household 

members have available for personal use? 

Please don’t count cell phones that are 

used exclusively for business purposes," 

are considered to have a landline-only 

telephone status.
Series 1, No. 61  Page 93 

Language Line Services—A 

translation service that provided real-time 

translation of the National Immunization 

Survey computer-assisted telephone 

interview into languages other than 

English and Spanish.

MenACWY or MCV—Meningococcal 

conjugate vaccine or meningococcalunknown type vaccine.

Metropolitan statistical area—

Geographic entities (sometimes called 

“metro areas”) defined by the Office 

of Management and Budget for use by 

federal statistical agencies collecting, 

tabulating, and publishing federal 

statistics. A metro area contains a core 

urban area of 50,000 or more population. 

Each metro area consists of one or 

more counties and includes the counties 

containing the core urban area, as well 

as any adjacent counties that have a high 

degree of social and economic integration 

(as measured by commuting to work) 

with the urban core. 

MMR—Measles, mumps, and rubella 

vaccine.

Monte Carlo simulation—Methods 

(or experiments) referring to a class of 

computational algorithms that rely on 

repeated random sampling to compute 

their results. Monte Carlo methods are 

often used in computer simulations of 

physical and mathematical systems.

Marketing Systems Group—A 

company that provides products and 

services for the survey research industry. 

Examples of products and services 

include landline and cell-phone randomdigit-dialing samples, address-based and 

list samples, sample or list enhancement 

services, and telephone screening 

services.

National Center for Health 

Statistics—An organizational component 

within the Centers for Disease Control 

and Prevention with the mission to 

provide statistical information that will 

guide actions and policies to improve the 

health of the American people.

National Center for Immunization 

and Respiratory Diseases—

Organizational component within 

the Centers for Disease Control and 

Prevention with the mission to prevent 

disease, disability, and death through 

immunization and by control of 

respiratory and related diseases.

National Health Interview Survey 

(NHIS)—Conducted by the National 

Center for Health Statistics since 1957 to 

monitor the health of the country. NHIS 

collects data through personal household 

interviews on a broad range of health 

topics. Data are collected by the U.S. 

Census Bureau. Survey results have been 

instrumental in providing data to track 

health status, health care access, and 

progress toward achieving national health 

objectives.

National Health Interview 

Survey–Provider Record Check 

(NHIS–PRC)—Conducted as part of 

the National Immunization Survey 

(NIS) to examine sampling strategies 

to address concerns related to potential 

coverage and nonresponse bias. The 

project aims to explore the impact on 

estimated vaccination coverage rates of 

nonresponse and undercoverage of the 

NIS target populations.

National Immunization Program—

An organizational component of 

the Centers for Disease Control and 

Prevention. The agency’s name changed 

in 2006 to the National Center for 

Immunization and Respiratory Diseases.

National Immunization Survey 

(NIS)—A family of surveys sponsored 

by the National Center for Immunization 

and Respiratory Diseases. The surveys 

include NIS–Child, NIS–Teen, and NIS–

Flu. 

National Survey of Children with 

Special Health Care Needs—A module 

of the State and Local Area Integrated 

Telephone Surveys, which is conducted 

by the National Center for Health 

Statistics. This survey was designed 

to produce national and state-specific 

prevalence estimates of children with 

special health care needs (CSHCN), 

describe the types of services that they 

need and use, and assess aspects of the 

system of care for CSHCN. The Maternal 

and Child Health Bureau of the Health 

Resources and Services Administration 

provided funding for this survey. It was 

conducted in 2001, 2005–2006, and 

2009–2010.

National H1N1 Flu Survey—A 

random-digit-dialing telephone survey 

conducted in 2009 and designed to 

produce timely, ongoing statistics on 

vaccination coverage of the population 

along with information concerning 

knowledge, attitudes, and behaviors 

related to the pH1N1 virus and its 

prevention.

NIS–Adult—National Immunization 

Survey Adult. A landline random-digitdialing telephone survey of adults 

conducted during May, June, July, and 

August 2007.

NIS–CIM—National Immunization 

Survey–Child Influenza Module. A 

short flu vaccination questionnaire 

administered to the NIS screening sample 

from October through June each year 

for children aged 6–18 months and 3–12 

years who are not eligible for NIS–Child 

or NIS–Teen.

NIS–Child—National Immunization 

Survey–Child. A list-assisted randomdigit-dialing telephone survey followed 

by a mailed survey to children’s 

immunization providers (the provider 

record check). The survey, which 

began data collection in April 1994, 

monitors childhood (ages 19–35 months) 

vaccination coverage in the United States 

and in U.S. territories.

NIS–Flu—National Immunization 

Survey–Flu. Combines the flu 

vaccination responses collected from 

NIS–Child (children aged 19–35 

months), NIS–Teen (adolescents aged 

13–17), and NIS–CIM ([child influenza 

module] children aged 6–18 months and 

3–12 years). NIS–Flu data are used to 

assess annual flu vaccination coverage 

among children aged 6 months–17 years 

at the national, state, and selected local 

levels and in some U.S. territories. These 

estimates are based on data reported by 

the child’s parent or guardian.

NIS–Teen—National Immunization 

Survey–Teen. Monitors vaccination 

coverage of adolescents aged 13–17. The 

survey uses a subsample of NIS–Child 

households, and the household and 

provider questionnaires were modeled 

after the corresponding NIS–Child 

instruments. NIS–Teen began data 

collection as an ongoing state-level 

survey in 2008.

Noncoverage—Occurs when the 

sampling frame does not fully cover the 

eligible population.

Nonresponse bias—Occurs in 

statistical surveys or censuses if the 

answers of respondents differ from the 
Page 94  Series 1, No. 61

potential answers of those who did not 

answer.

Parental concerns module—

Added to the National Immunization 

Survey to assess and understand 

parents' perceptions related to vaccines 

administered to infants and toddlers, 

satisfaction with visits to providers, 

influences on decisions about vaccinating 

children, and influences on decisions 

by some to delay or refuse vaccinations 

altogether.

PCV—Pneumococcal vaccine.

Phoneless—A household that has no 

telephone service.

Polio—Poliovirus.

Ported number—A telephone number 

that has been transferred from one carrier 

to another, from one location to another, 

or from one service type to another. In 

this report, the term refers exclusively 

to a transfer between landline and cellphone service.

Prefix area or exchange—Bank of 

10,000 consecutive telephone numbers 

with suffix in the range 0000–9999.

Provider—Doctor, nurse, or health 

care provider responsible for the child's 

health and vaccinations.

Provider-phase weight—A set of 

survey weights applied to all children or 

adolescents for whom adequate provider 

data were obtained. The providerphase weight allows for estimation of 

vaccination status and other variables 

obtained from the National Immunization 

Survey provider record check.

Provider record check (PRC)—

Follow-on mail survey of vaccination 

providers identified by household 

respondents. The PRC survey is mailed 

to vaccination providers to obtain the 

vaccination history for the National 

Immunization Survey-eligible children 

for which consent to contact the provider 

was obtained from the parents or 

guardians in the household telephone 

interview.

Proxy cell-phone-only—A household 

that has a landline telephone and has 

similar (as identified via a logistic 

regression model) characteristics as a 

cell-phone-only household.

Random-digit dialing (RDD)—

Method for selecting people in telephone 

statistical surveys by generating 

telephone numbers at random, using 

telephone exchange information. RDD 

has the advantage that it includes unlisted 

numbers that would be missed if the 

numbers were selected from a phone 

directory. In populations where there is a 

high telephone-ownership rate, it can be 

a cost-efficient way to obtain complete 

coverage of a geographic area.

RDD-phase weight—A set of 

survey weights applied to all children 

or teenagers for whom a completed 

household interview was obtained. The 

RDD-phase weight allows for estimation 

of variables obtained from the National 

Immunization Survey household 

interview.

Realization rate—An alternative 

measure of potential bias in surveys 

that does not suffer from the limitations 

encountered by the response rate. It 

takes into account the potential bias 

from nonresponse as well as frame 

undercoverage. It is defined as the ratio 

of the unadjusted survey estimate of the 

size of the target population to the true 

size of that population, as obtained from 

an external source.

Resolution rate—For a random-digitdialing sample, the number of selected 

telephone numbers resolved as residential 

or nonresidential as a proportion of the 

total number of telephone numbers in the 

sample.

Response rate—Often response 

rates in survey research are calculated 

by dividing the number of completed 

interviews by the number of individuals 

who were selected to participate in the 

research. However, this method is too 

simplistic and does not do justice to the 

complexity of research design, sampling 

process, and the practical difficulties 

of contacting and assessing potential 

survey participants. As a result, the 

Council of American Survey Research 

Organizations (CASRO) proposed a 

method to better consider the various 

situations encountered in survey 

research. This method formed the basis 

for the development of a standard for 

the calculation of response rates by the 

American Association for Public Opinion 

Research. 

Generally, the response rate is 

defined as the number of completed 

interviews divided by the number 

of cases eligible to take the survey. 

Specifically, the CASRO response 

rate for the National Immunization 

Survey is the product of the resolution 

rate, screener completion rate, and the 

interview completion rate.

RV—Rotavirus vaccine.

Screener completion rate—For a 

random-digit-dialing sample, the number 

of households screened as eligible or 

ineligible as a proportion of the total 

resolved residential telephone numbers in 

the sample.

Screener nonrespondent—

Households or people for whom the 

screener portion of the survey that 

determines eligibility for the National 

Immunization Survey was not completed.

Section 317 Program—A 

discretionary program funded by 

Congress to support immunization 

infrastructure (activities to increase and 

sustain immunization coverage rates in 

the population) and vaccine purchase for 

underinsured children and adults. This 

grant (cooperative agreement) award 

program is administered by the Centers 

for Disease Control and Prevention and 

implemented by 64 grantees: 50 states, 8 

territories (the Commonwealth of Puerto 

Rico, the Virgin Islands, Guam, the 

Northern Mariana Islands, the Federated 

States of Micronesia, the Republic of the 

Marshall Islands, the Republic of Palau, 

and American Samoa), and 6 urban areas 

(Chicago, Houston, Bexar County [San 

Antonio], New York City, Philadelphia 

County, and Washington, D.C.).

Socioeconomic status module—

Assesses the contributions of 

socioeconomic status indicators to racial 

and ethnic and poverty disparities in 

vaccination coverage.

State and Local Area Integrated 

Telephone Survey—Collects important 

health care data at the state and local 

levels. The National Center for Health 

Statistics developed this data-collection 

mechanism, which uses the large 

National Immunization Survey screening 

sample. Survey modules fielded with 

this mechanism supplement national 

data-collection strategies by providing 

in-depth state and local area data to meet 

various program and policy needs.
Series 1, No. 61  Page 95 

Synthesized estimates—Estimates 

for children computed using adequate 

provider data from the National 

Immunization Survey or adequate 

provider data from a state or local 

immunization information system.

TD or Tdap—Tetanus and diphtheria 

toxoid vaccine (Td); tetanus toxoid, 

reduced diphtheria toxoid, and acellular 

pertussis (Tdap); or tetanus-unknown 

vaccine at or after age 10 years.

Teen-level analysis file—Annual file 

created for NIS–Teen, using processing 

and estimation procedures similar to 

those used to produce NIS–Child childlevel analysis file, including matching 

sheet review, creation of up-to-date 

variables, imputation, and weighting.

Telephone Consumer Protection Act 

of 1991—A list of rules for telemarketers 

to follow when contacting consumers via 

telephone. This includes 1) limiting calls 

to between 8 a.m. and 9 p.m., 2) adhering 

to do-not-call lists and keeping this list 

indefinitely, and 3) having a clearly 

written policy available.

Telephone hundred bank—A group 

of 100 consecutive telephone numbers. 

Each bank is grouped by area code, threedigit prefix, and the first two digits of the 

suffix.

Telephone status—Refers to whether 

the household has no telephone service, 

only landline telephone service, only 

cell-phone service, or has both landline 

and cell telephone service. For those 

with both types of service, telephone 

status can be further separated based on 

whether calls are answered mostly using 

the landline, mostly the cell phone, or 

nearly equal for both (see definition for 

“balanced dual user”). The Figure in 

this appendix depicts the spectrum of 

telephone statuses diagram.

Top coding—The suppression of 

extremely high values by resetting these 

values to be equal to a predetermined 

maximum upper bound. Top coding is 

a method used to protect confidentiality 

and reduce disclosure risk of respondents 

with unique sociodemographic 

characteristics. For example, respondents 

with very high reported income are topcoded.

Topical modules—Additional sets of 

questions to the National Immunization 

Survey (NIS) to learn more about parents’ 

concerns about vaccines and financial 

barriers to becoming vaccinated. Topical 

modules that have been administered 

since 2004 as part of the NIS–Child 

household interviews include the Health 

Insurance Module, the Parental Concerns 

Module, and the Socioeconomic Status 

Module. The Health Insurance Module 

has been incorporated into the core NIS 

survey since 2006.

Total survey error—Includes all 

forms of survey error, including sampling 

variability, interviewer effects, frame 

errors, response bias, and nonresponse 

bias.

Undercoverage—The existence of 

members of the population that do not 

appear in the sampling frame and cannot 

be selected for the interview (e.g., nophone households).

Unit nonresponse—A missing 

response for all questionnaire items due 

to noncontact or refusal to participate in 

the survey.

Unresolved telephone number—A 

selected telephone number for which it is 

not possible to determine, through initial 

contact attempts, whether it is residential 

or nonresidential.

UTD—A child or teenager is up to 

date (UTD) if recommendations from the 

Advisory Committee for Immunization 

Practices for vaccinations for the child or 

teenager are met.

Vaccines for Children (VFC) 

Program—Provides financially entitled 

children with publicly purchased vaccines 

at no cost at the offices and clinics of 

vaccination providers who are enrolled 

in the VFC Program. Children aged 18 

years and under are entitled to receive 

VFC vaccines if they are a) eligible for 

Medicaid, b) not covered by any health 

insurance that pays for doctor visits and 

hospital stays (“uninsured”), c) American 

Indian or Alaska Native, or d) covered 

by private health insurance that does 

not cover the costs of all recommended 

vaccines aside from copays, deductibles, 

and vaccination administration fees 

(“underinsured”) and are vaccinated at a 

federally qualified health center or a rural 

health center.

Var—Varicella.

Working residential number rate—

For a random-digit-dialing sample, the 

number of residential telephone numbers 

as a proportion of the total number 

of resolved telephone numbers in the 

sample.

Zero-bank—A group of telephone 

hundred banks with no listed residential 

number.

 

Figure. Spectrum of telephone statuses
Page 96  Series 1, No. 61

Zero-shot child—A child is 

considered to be “zero-shot” if 1) the 

household respondent reported zero 

vaccinations for the child and identified 

zero providers; or 2) the household 

respondent reported zero vaccinations 

for the child and identified one or 

more providers, all of the identified 

providers returned immunization history 

questionnaires or medical records, and 

none of the providers reported any 

vaccinations for the child.
Vital and Health Statistics

Series Descriptions

Active Series

Series 1. Programs and Collection Procedures

Reports describe the programs and data systems of the 

National Center for Health Statistics, and the data collection 

and survey methods used. Series 1 reports also include 

definitions, survey design, estimation, and other material 

necessary for understanding and analyzing the data.

Series 2. Data Evaluation and Methods Research

Reports present new statistical methodology including 

experimental tests of new survey methods, studies of vital and 

health statistics collection methods, new analytical techniques, 

objective evaluations of reliability of collected data, and 

contributions to statistical theory. Reports also include 

comparison of U.S. methodology with those of other countries.

Series 3. Analytical and Epidemiological Studies

Reports present data analyses, epidemiological studies, and 

descriptive statistics based on national surveys and data 

systems. As of 2015, Series 3 includes reports that would 

have previously been published in Series 5, 10–15, and 20–23.

Discontinued Series

Series 4. Documents and Committee Reports

Reports contain findings of major committees concerned with 

vital and health statistics and documents. The last Series 4 

report was published in 2002; these are now included in 

Series 2 or another appropriate series.

Series 5. International Vital and Health Statistics Reports

Reports present analytical and descriptive comparisons of 

U.S. vital and health statistics with those of other countries. 

The last Series 5 report was published in 2003; these are now 

included in Series 3 or another appropriate series.

Series 6. Cognition and Survey Measurement

Reports use methods of cognitive science to design, evaluate, 

and test survey instruments. The last Series 6 report was 

published in 1999; these are now included in Series 2.

Series 10. Data From the National Health Interview Survey

Reports present statistics on illness; accidental injuries; 

disability; use of hospital, medical, dental, and other services; 

and other health-related topics. As of 2015, these are included 

in Series 3.

Series 11. Data From the National Health Examination Survey, the 

National Health and Nutrition Examination Surveys, and 

the Hispanic Health and Nutrition Examination Survey

Reports present 1) estimates of the medically defined 

prevalence of specific diseases in the United States and the 

distribution of the population with respect to physical, 

physiological, and psychological characteristics and 2) 

analysis of relationships among the various measurements. 

As of 2015, these are included in Series 3.

Series 12. Data From the Institutionalized Population Surveys

The last Series 12 report was published in 1974; these reports 

were included in Series 13, and as of 2015 are in Series 3.

Series 13. Data From the National Health Care Survey

Reports present statistics on health resources and use of 

health care resources based on data collected from health 

care providers and provider records. As of 2015, these reports 

are included in Series 3.

Series 14. Data on Health Resources: Manpower and Facilities

The last Series 14 report was published in 1989; these reports 

were included in Series 13, and are now included in Series 3.

Series 15. Data From Special Surveys

Reports contain statistics on health and health-related topics 

from surveys that are not a part of the continuing data systems 

of the National Center for Health Statistics. The last Series 15 

report was published in 2002; these reports are now included 

in Series 3.

Series 16. Compilations of Advance Data From Vital and Health 

Statistics

The last Series 16 report was published in 1996. All reports 

are available online; compilations are no longer needed.

Series 20. Data on Mortality

Reports include analyses by cause of death and demographic 

variables, and geographic and trend analyses. The last Series 

20 report was published in 2007; these reports are now 

included in Series 3.

Series 21. Data on Natality, Marriage, and Divorce

Reports include analyses by health and demographic 

variables, and geographic and trend analyses. The last Series 

21 report was published in 2006; these reports are now 

included in Series 3.

Series 22. Data From the National Mortality and Natality Surveys

The last Series 22 report was published in 1973. Reports from 

sample surveys of vital records were included in Series 20 or 

21, and are now included in Series 3.

Series 23. Data From the National Survey of Family Growth

Reports contain statistics on factors that affect birth rates, 

factors affecting the formation and dissolution of families, and 

behavior related to the risk of HIV and other sexually 

transmitted diseases. The last Series 23 report was published 

in 2011; these reports are now included in Series 3.

Series 24. Compilations of Data on Natality, Mortality, Marriage, and 

Divorce

The last Series 24 report was published in 1996. All reports 

are available online; compilations are no longer needed.

For answers to questions about this report or for a list of reports published 

in these series, contact:

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