National Center for Health Statistics

Impact of the COVID-19 Pandemic on National Center 

for Health Statistics Data Collections

Denys T Lau, PhD

Senior Science Advisor

Division of Health and Nutrition Examination Surveys

National Center for Health Statistics

FCSM 2021 Research and Policy Conference 

November 2, 2021
Public Health Data Systems

▪ Surveillance and survey data track major life events such as births 

and deaths, disease distribution, and health care utilization. 

▪ Various data systems track different aspects of COVID-19. 

– See CDC COVID Data Tracker1

▪ Examples of COVID-19 data: 

– Cases from notifiable infectious disease systems

– Deaths from vital statistics systems

– Hospitalizations from 6000+ hospitals compiled in the Unified 

Hospital Time-Series Dataset

1 www.cdc.gov/coronavirus/2019-ncov/cases-updates/index.html
Sampled In-Care Data

▪ To understand the epidemiology of COVID-19 among in-care 

populations, more in-depth information is needed. 

▪ Collecting representative sampled data is a necessary alternative. 

▪ For example:

– Claim and electronic health record data are gathered from a 

national sample of hospitals in the National Hospital Care Survey. 

– Multi-modal surveys of a national sample of adult day services 

centers and of residential care communities in the National PostAcute and Long-Term Care Survey.
Sampled Household Data

▪ Many individuals with COVID-19 can be asymptomatic or exhibit 

mild symptoms, many Americans may be undiagnosed.1

▪ To more fully understand the epidemiology of COVID-19,

– A national sample survey with the capacity to conduct 

antibody tests, like the National Health and Nutrition 

Examination Survey, can provide information on diagnosed 

and undiagnosed COVID-19 cases.

1 Kalish H et al. Undiagnosed SARS-CoV-2 seropositivity during the first 6 months of the COVID-19 

pandemic in the United States. Sci Transl Med. 2021. https://doi.org/10.1126/scitranslmed.abh3826
COVID-19’s Iマpact oミ NCHS Data

▪ These systems of health data collection aim to track different 

aspects of COVID-19 to meet data needs of diverse users. 

▪ Due to COVID-19 safety concerns, public health data collection 

and processing were disrupted. 

▪ In this session, representatives from NCHS discussed:

– How COVID-19 affected their operations

– What modifications were made in response to the pandemic
Addressing Data Quality

▪ While each NCHS program took unique approaches to modify 

their protocols, all addressed key dimensions of data quality:

– Accuracy and consistency

– Timeliness

– Efficiency and burden

– Relevance
Data Accuracy and Consistency

▪ Early in COVID-19, NCHS survey operations entailing in-person 

interactions were switched, where feasible, to phone/online interviews. 

– In-person data collection resumed after safety measures were 

instituted and in areas with low concentrations of COVID-19 cases. 

▪ Efforts were made to minimize disruption and track impact of switching 

data collection modes on accuracy, consistency and completeness. 

– Assessing the effect of phone contacts on response rates and bias in 

the National Health Interview Survey (NHIS)
Timely Data Dissemination

▪ Where possible, some NCHS programs took unprecedented steps 

to release preliminary data before the release of official data files. 

– NCHS provided preliminary data on their COVID-19 dashboard 

for a subsample of hospitals that report to the National 

Hospital Care Survey. 
Data Efficiency and Burden

▪ Due to expected delay in releasing NHIS data files during the 

pandemic, NCHS turned to a new online data collection platform. 

– The Research and Development Survey produced 

experimental estimates about COVID-19 relatively quickly.

– NCHS partnered with the Census Bureau to include COVID-19-

related content on the new Household Pulse Survey.1

• Online data collection is less costly to administer and may 

be more convenient for respondents. 

1 www.census.gov/data/experimental-data-products/household-pulse-survey.html
Data Relevance

▪ Timely changes were made to NCHS surveys to replace less-prioritized 

content with new COVID-19–related items to monitor the pandemic. 

– National Health and Nutrition Examination Survey added new 

COVID-19–related items.

• Most notably, antibody testing to produce national estimates on 

natural COVID-19 infections and on vaccine-induced immunity 

– National Health Care Surveys included new items about health care 

providers’ experieミces duriミg the paミdeマic.

• Telemedicine, personal protective equipment, and knowledge 

about fellow providers/staff testing positive for COVD-19
Conclusion

▪ NCHS data programs have demonstrated agility, resilience, innovation, 

and commitment in their efforts to meet their mission, 

– Incorporating new COVID-19–related items to monitor the pandemic 

– Implementing new data collection, processing, and dissemination 

plans to release data in an even more timely manner

▪ As more data become available, NCHS can further examine:

– Impact of changes made to its data systems on data quality

– Extent and impact of COVID-19 on the health of the nation
Thank you!

Contact information:

Denys T Lau

wyr1@cdc.gov

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