Effectiveness of Adacel Vaccination in Pregnancy at Preventing Pertussis in Infants < 2 Months of Age in the United States

Study Overview
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Brief Summary
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The purpose of this study is to determine the effectiveness of Adacel against pertussis disease in infants < 2 months when administered during pregnancy following the current Advisory Committee on Immunization Practices (ACIP) recommendations, i.e., from 27 to 36 weeks of gestation, and 14 days or more before delivery.

Detailed Description
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The original study included cases recorded from 01 January 2011 through 31 December 2014, based on retrospective case-control methodology.

Official Title
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Effectiveness of Adacel Vaccination in Pregnancy at Preventing Pertussis in Infants < 2 Months of Age in the United States (US)

Conditions
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Pertussis (Whooping Cough)

Intervention / Treatment
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* Other: Not applicable / dataset analysis


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Cases were included if they met the following inclusion criteria: Reported pertussis disease in the referenced EIP surveillance database Age greater than 2 days and younger than two months of age Resided in the catchment area on date of onset of their cough Born in a hospital in their state of residence ≥ 37 weeks of gestation at birth Not adopted, in foster care or living in a residential care facility Completed maternal interview Completed infant and maternal information Controls were included if they met the following inclusion criteria: Age greater than 2 days and younger than 2 months of age on date of cough onset for the corresponding case infant Resided in the catchment area on date of cough onset for the corresponding case infant Born in a hospital in their state of residence ≥ 37 weeks of gestation at birth Not adopted, in foster care or living in a residential care facility Maternal interview completed Infant and maternal information complete Exclusion Criteria: Cases were excluded if they met any of the following exclusion criteria: Vaccination status of the mother unknown Infants whose mothers were vaccinated with Boostrix or an unknown vaccine brand Controls were excluded if they met any of the following exclusion criteria: Vaccination status of the mother unknown A pertussis diagnosis prior to the cough onset date of the corresponding case infant Controls that were matched to Boostrix or an unknown brand cases

Ages Eligible for Study
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Minimum Age: 2 Days
Maximum Age: 2 Months

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Pertussis Case Group<br>Infants between 2 days to less than 2 months of age for whom a case of pertussis was reported (laboratory confirmed pertussis, epidemiological linkage to a laboratory-confirmed case and/or clinically compatible illness) and who met case inclusion criteria. This post-hoc analysis was limited to infants born of mothers vaccinated with Adacel or who did not receive any tetanus, diphtheria, and acellular pertussis (Tdap) vaccine. | Other: Not applicable / dataset analysis<br>* Not applicable / dataset analysis<br>|
| Control Group<br>Infants born at the same hospital as the case-infant who were less than 2 months old on the case-infant's cough onset date, and who met control inclusion criteria. This post-hoc analysis was limited to infants born of mothers vaccinated with Adacel or who did not receive any Tdap vaccine. | Other: Not applicable / dataset analysis<br>* Not applicable / dataset analysis<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of pertussis cases in infants less than 2 months and matched controls | Vaccine effectiveness at preventing pertussis in infants less than 2 months of age was estimated using conditional logistic regression. | During the data collection period (from 01 January 2011 to 31 December 2014) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of pertussis cases requiring hospitalization in infants less than 2 months and matched controls | Vaccine effectiveness at preventing pertussis requiring hospitalization was estimated using conditional logistic regression | During the data collection period (from 01 January 2011 to 31 December 2014) |