COVID-Related Content, COVID-related NHIS Study Design Changes, and the 2019-2020 Longitudinal Sample
Additional COVID-related content
Starting in quarter 3 of 2020, NCHS began to add questions related to COVID-19 to the NHIS questionnaire. These questions are related either directly to COVID-19, or to the social, economic, and healthcare ramifications of the pandemic. The tables below list each variable, the question number and text, whether they are available for the sample adult and sample child, and the calendar quarter in which the question was introduced. It is important for users to make special note of questions that were not available for a full calendar year to ensure correct weighting in their analyses. Each table groups variables by their potential field of interest.
Table 1. COVID Symptoms and Diagnosis
Table 3. Access to Care During the COVID-19 Pandemic
Table 4. Employment and Social Distancing at Work
Table 5. Wellbeing and Social/Emotional Support
Table 1. COVID symptoms and diagnosis
| IPUMS Variable | Question ID | Text | Sample Adult | Sample Child | Quarter Introduced |
|---|---|---|---|---|---|
| CVDDIAG | CVD.0020.00.4 | Has a doctor or other health professional ever told [you/SAMPLE CHILD'S NAME] that you had or likely had coronavirus or COVID-19? | X | X | 2020 Q3 |
| CVDTEST | CVD.0030.00.4 | Have [you/SAMPLE CHILD'S NAME] ever been tested for coronavirus or COVID-19? | X | X | 2020 Q3 |
| CVDTESTRSLT | CVD.0040.00.4 | Did the test find that [you/SAMPLE CHILD'S NAME] had coronavirus or COVID-19? | X | X | 2020 Q3 |
| CVDSYMP | CVD.0050.00.4 | How would you describe [your/SAMPLE CHILD'S NAME] coronavirus symptoms when they were at their worst? Would you say no symptoms, mild symptoms, moderate symptoms, or severe symptoms? | X | X | 2020 Q3 |
| CVDLOSESMELL | TSC.0010.00.3 | When you had coronavirus, did you lose some or all of your sense of smell or did you smell odors that were not there? | X | 2021 Q1 | |
| CVDRECSMELL | TSC.0020.00.3 | Has your sense of smell fully recovered, partially recovered, or not recovered at all? | X | 2021 Q1 | |
| CVDLOSETASTE | TSC.0030.00.3 | When you had coronavirus, did you lose some or all of your ability to taste or did you have unwanted tastes or sensations in your mouth that did not go away? | X | 2021 Q1 | |
| CVDRECTASTE | TSC.0040.00.3 | Has your ability to taste fully recovered, partially recovered, or not recovered at all? | X | 2021 Q1 |
Table 2. COVID vaccination
| IPUMS Variable | Question ID | Text | Sample Adult | Sample Child | Quarter Introduced |
|---|---|---|---|---|---|
| CVDSHT | IMS.0061.00.3 | Have [you/SAMPLE CHILD'S NAME] had a COVID-19 vaccination? | X | X | SA: 2021 Q2 SC: 2021 Q3 |
| CVDSHTNUM | IMS.0062.00.3 | How many COVID-19 vaccinations have [you/SAMPLE CHILD'S NAME] received? | X | X | SA: 2021 Q2 SC: 2021 Q3 |
| CVDMODOSE1 CVDYRDOSE1 | IMS.0063.01.3 IMS.0063.02.3 | During what month and year did [you/SAMPLE CHILD'S NAME] receive your most recent COVID-19 vaccination? | X | X | SA: 2021 Q2 SC: 2021 Q3 |
| CVDMODOSE2 CVDYRDOSE2 | IMS.0064.01.3 IMS.0064.02.3 | During what month and year did [you/SAMPLE CHILD'S NAME] receive your next most recent COVID-19 vaccination? | X | X | SA: 2021 Q2 SC: 2021 Q3 |
| CVDSHTADD | IMS.0065.00.3 | Did a doctor or other health professional tell [you/SAMPLE CHILD'S NAME] that you need an additional dose of the COVID-19 vaccination? | X | X | SA: 2021 Q2 SC: 2021 Q3 |
| CVDSHTTYPE1 | IMS.0065.00.3 | For your first shot, which brand of COVID-19 vaccine did you receive? | X | X | 2022 Q4 |
Table 3. Access to care during the COVID-19 pandemic
| IPUMS Variable | Question ID | Text | Sample Adult | Sample Child | Quarter Introduced |
|---|---|---|---|---|---|
| CVDDLYCARE | ACC.0010.00.4 | Was there any time when [you/SAMPLE CHILD'S NAME] DELAYED getting medical care because of the coronavirus pandemic? | X | X | 2020 Q3 |
| CVDDNGCARE | ACC.0020.00.4 | Was there any time when [you/SAMPLE CHILD'S NAME] needed medical care for something other than coronavirus, but DID NOT GET IT because of the coronavirus pandemic? | X | X | 2020 Q3 |
| VIRAPP12M | ACC.0030.00.4 | In the past 12 months, have [you/SAMPLE CHILD'S NAME] had an appointment with a doctor, nurse, or other health professional by video or by phone? | X | X | 2020 Q3 |
| CVDVIRAPPCVD | ACC.0040.00.4 | Were any of [your/SAMPLE CHILD'S NAME] appointments done by video or by phone because of reasons related to the coronavirus pandemic? | X | X | 2020 Q3 |
| CVDDNGHMECARE | CGR.0010.00.4 | Was there any time when you needed care at home from a nurse or other health professional but DID NOT GET IT because of the coronavirus pandemic? | X | 2020 Q3 | |
| CVDFAMCAR12M | CGR.0020.00.4 | During the past 12 months, did you receive care at home from a friend or family member? | X | 2020 Q3 | |
| CVDDNGFAMCAR | CGR.0030.00.4 | Was there any time when you needed care at home from a friend or family member but DID NOT GET IT because of the coronavirus pandemic? | X | 2020 Q3 | |
| CVDFAMCAREPR | CGR.0040.00.4 | Did a friend or family member provide some or all of the care that a nurse or other health professional did not provide due to the coronavirus pandemic? | X | 2020 Q3 | |
| CVDCANTREA | CNV.0010.00.3 | At any time since the start of the coronavirus pandemic, were you in treatment or supposed to receive treatment for your cancer? | X | 2020 Q3 | |
| CVDCANCHG | CNV.0020.00.3 | Were any of your treatments for cancer changed, delayed, or cancelled because of the coronavirus pandemic? | X | 2020 Q3 | |
| CVDCANOTHTR | CNV.0030.00.3 | As a cancer patient or cancer survivor, you may need OTHER medical care related to your cancer such as lab visits, imaging, monitoring visits, rehabilitation, physical therapy, care for side-effects, or visits with medical specialists. At any time since the start of the coronavirus pandemic, did you need any of this OTHER medical care related to your cancer? | X | 2020 Q3 | |
| CVDCANOTHCHG | CNV.0040.00.3 | Was any of this OTHER medical care related to your cancer changed, delayed, or cancelled because of the coronavirus pandemic? | X | 2020 Q3 |
Table 4. Employment and social distancing at work
| IPUMS Variable | Question ID | Text | Sample Adult | Sample Child | Quarter Introduced |
|---|---|---|---|---|---|
| WRKSICKDAY | JOB.0080.00.3 | During the past 3 months, how many days did you work while physically ill? | X | 2021 Q1 | |
| WLDAYSICK | JOB.0090.00.3 | During the past 3 months, about how many days of work did you miss because you were ill or because there was chance you had COVID-19? | X | 2021 Q1 | |
| CVDCURJOBSD | SDW.0010.00.3 | Thinking about your MAIN job or business, are there currently social distancing measures in effect to help keep people apart? | X | 2020 Q3 | |
| CVDWCLSDCUR | SDW.0020.00.3 | Currently, at your MAIN job or business, how often do you still need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? | X | 2020 Q3 | |
| CVDWCLNOSD | SDW.0030.00.3 | When social distancing measures were NOT in effect,how often did you need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? | X | 2020 Q3 | |
| CVDWCLOFT | SDW.0040.00.3 | Currently, at your MAIN job or business, how often do you need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? | X | 2020 Q3 | |
| CVDJOBSDEV | SDW.0050.00.3 | At any time since the start of the coronavirus pandemic, did your MAIN job or business put social distancing measures into effect? | X | 2020 Q3 | |
| CVDWCLSDOF | SDW.0060.00.3 | When social distancing measures were in effect, how often did you need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? | X | 2020 Q3 | |
| CVDMNJOBSD12M | SDW.0070.00.3 | Thinking about the MAIN job you held in the past 12 months, were there ever any social distancing measures in effect while you worked there? That is, were there ever practices in place to help keep people apart? | X | 2020 Q3 | |
| CVDWCLSD12M | SDW.0080.00.3 | When social distancing measures were in effect, how often did you still need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? | X | 2020 Q3 | |
| CVDWCLNOSD12M | SDW.0090.00.3 | When social distancing measures were NOT in effect, how often did you need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? | X | 2020 Q3 | |
| CVDWCLSOFT12M | SDW.0100.00.3 | How often did you need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? | X | 2020 Q3 |
Table 5. Wellbeing and Social/Emotional support
| IPUMS Variable | Question ID | Text | Sample Adult | Sample Child | Quarter Introduced |
|---|---|---|---|---|---|
| DIADISTRESS | DIB.0140.00.3 | During the past month, how often have you felt overwhelmed by the demands of living with diabetes? Would you say always, usually, sometimes, rarely, or never? | X | 2021 Q1 | |
| DIACVDSTRESS | DIB.0150.00.3 | Compared with the time before the coronavirus pandemic, would you say that you now feel more overwhelmed by the demands of living with diabetes, less overwhelmed, or about the same as before the pandemic? | X | 2021 Q1 | |
| EMOSUPPORT | SOS.0010.00.4 | How often do you get the social and emotional support you need? Would you say always, usually, sometimes, rarely, or never? | X | X | SA: 2020 Q3 SC: 2021 Q1 |
| CMPSUPPORT | SOS.0020.00.4 | Compared with 12 months ago, would you say that you now receive more social and emotional support, less social and emotional support, or about the same? | X | X | SA: 2020 Q3 SC: 2021 Q1 |
Table 6. Long COVID
| IPUMS Variable | Question ID | Text | Sample Adult | Sample Child | Quarter Introduced |
|---|---|---|---|---|---|
| CVDLONG | CVL.0050.00.4 | Did you have any symptoms lasting 3 months or longer that you did not have prior to having coronavirus or COVID-19? | X | X | 2022 Q1 |
| CVDLONGNOW | CVL.0060.00.4 | Do you have symptoms NOW? | X | X | 2022 Q1 |
COVID-Related NHIS Study Design Changes
The National Center for Health Statistics continued to field the NHIS throughout 2020 with several notable changes to data collection and questionnaire content to accommodate COVID and COVID-related nonresponse.
The National Center for Health Statistics (NCHS) fielded four separate NHIS study designs during the course of 2020:
- 1) Normal, in-person data collection in quarter 1,
- 2) Telephone-only in quarter 2,
- 3) Telephone-first in quarters 3 and 4, and
- 4) The introduction in August 2020 of a longitudinal sample while maintaining part of the original 2020 sample.
Below, we describe the study design changes at various points in 2020, describe the longitudinal and partial samples, and provide an overview of COVID-related content introduced during 2020. For additional information and updates, please refer to the NCHS website on NHIS 2020 data collection efforts.
Changes to Interviewing Procedures
NHIS data are typically collected as an in-person interview. Between mid-March and July (quarter 2), the NHIS temporarily became a telephone-only survey. While the telephone-only approach was in the field, household interview response rates dropped from 60% in calendar quarter 1 of 2020 to 42.7% in quarter 2; sample adult and sample child interview response rates fell from 57.9% to 41.1% and 57.6% to 40.1%, respectively (Dahlhamer et al., 2021). In July, a telephone-first approach was implemented in selected areas, and then rolled out in all areas in September. Under the telephone-first approach, household contacts were still attempted by telephone first, and personal visits were reserved for follow-up on nonresponse, to deliver recruitment materials, and to conduct interviews when telephone numbers were unknown. The telephone-first approach will continue for the foreseeable future.
During the time that NHIS was a telephone-only survey, survey response rates decreased from 60 to 43%. However, with the introduction of the telephone-first design, response rates have increased to 50-60%. Approximately 30% of interviews were conducted in-person in September 2020.
2019-2020 Longitudinal Sample
In light of changing response rates in 2020, NCHS chose to introduce a subsample of adults who had previously participated in the NHIS with known representativeness and nearly complete telephone contact information to inform weighting and estimation techniques that were use to produce official 2020 estimates. From August to December 2020, NCHS re-contacted by telephone a "longitudinal" sample of roughly 20,000 adult respondents who completed the NHIS in 2019 and invited them to complete the 2020 NHIS questionnaire. The longitudinal sample did not include sample children. 10,415 individuals from the longitudinal sample completed the 2020 NHIS questionniare. The longitudinal data collected on this sample allows users to evaluate health, health care, and well-being from before and during the pandemic. To free up resources to field the longitudinal sample, the size of the quarter 3 and 4 samples was reduced by half. Users may link an individual in the 2020 longitudinal sample to their record in the 2019 file by linking on the person's 2020 value of NHISPIDPRVYR and the person's 2019 value of NHISPID. Please see NHISPIDPRVYR for more information. LONGWEIGHT should be used in analyses evaluating individual-level changes between 2019 and 2020 among the same adults.
Partial Sample
The "partial" sample refers to the 21,153 individuals in the original 2020 sample. It excludes the individuals in the longitudinal sample who were also in the 2019 sample. The partial sample in combination with the longitudinal sample encompasses all 31,568 sample adults with a 2020 record. According to the 2020 Survey Description, PARTWEIGHT is only recommended for use with the 2020 data when producing estimates based on pooled 2019 and 2020 data to increase sample size; in that case SAMPWEIGHT should be used for the 2019 records. A user might, for example, create a new weight and assign PARTWEIGHT values for 2020 and SAMPWEIGHT values for 2019. SAMPWEIGHT should still be used to produce official estimates for 2020 or to compare estimates between 2019 and 2020.
Additional Resources
Dahlhamer JM, Bramlett MD, Maitland A, Blumberg SJ. Preliminary Evaluation of Nonresponse Bias Due to the COVID-19 Pandemic on National Health Interview Survey Estimates, April-June 2020. Hyattsville, MD: National Center for Health Statistics. February 2021.
SHADAC. NHIS: Early Release Estimates Show Unchanged Coverage Rates during First Half of 2020, although NCHS Reports Evidence of Nonresponse Bias due to COVID-19. February 15, 2021.
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