By Julia A. Rivera Drew
Collected annually since 1957, the National Health Interview Survey (NHIS) is the longest running nationally-representative health survey in the world. The NHIS questionnaire and data collection approaches have changed considerably over time, both to better capture emerging public health topics as well as to adapt the study design, questionnaire, and data collection operations to maintain a high-quality data product. The objective of this blog post is understanding the factors that contribute to year-to-year change in variables available from the NHIS with a particular focus on the 2025 NHIS data.
How is the NHIS structured?
Since 2019, the NHIS questionnaire has been a combination of (1) NHIS “core” content, collected every year; (2) NHIS “rotating core” content, collected on some predetermined occasional schedule; (3) NHIS “emerging public health” topical content, which is generally temporary and may be collected for a few consecutive years, collected occasionally, or collected once and then not again; and (4) NHIS “sponsored” content, with funding provided by other federal agencies. Refer to our user note on changes to the NHIS questionnaire implemented with the 2019 redesign for more information.
Why might specific variables be discontinued?
Changes to NHIS variables from one year to the next are by and large expected and due to intentional design choices or priorities of the question sponsors. One such intentional design choice is the implementation of rotating core content with the 2019 NHIS redesign. For example, a set of items on utilization of health care services such as dental, vision, and home health care is asked on a two-years-on-one-year-off rotation (e.g., DENTINT, “interval since last dental visit,” was collected in 2019-2020, skipped in 2021, collected in 2022-2023, skipped in 2024, and collection resumed in 2025). When a major change to NHIS core content is proposed, users are formally notified through a federal register notice (such as the recent federal notice about proposed changes to the NHIS questionnaire to be implemented in 2028).
The discontinuation of emerging public health and sponsored content is harder to predict. For example, the 2019 and 2020 questionnaires included three items of emerging public health content on using opioid use for pain, which quickly gave way in 2021 to a series of COVID-19 related measures designed to track important public health aspects of the pandemic, such as testing, infection, vaccination, social distancing, and social isolation. Sustaining sponsored content, where open-ended supplements are fielded on an annual or otherwise regular basis, is clearly distinguished from other, close-ended sponsored content in the NHIS documentation. However, even sustaining sponsors can reduce or completely end their support for long-running questions on the NHIS questionnaire with little notice, as was the case for the food security supplement items that have been sponsored by USDA for inclusion in the NHIS since 2011. The discontinuation of these items was disclosed at the beginning of 2025 and described in greater detail below.
IPUMS integrates new NHIS data into our collection and makes them available through the nhis.ipums.org website as quickly as possible. However, we frequently break the release of new NHIS data to the IPUMS NHIS website into two parts, adding continuing content first and new or modified content later. If we have not added a variable of interest to you, please consult the original NCHS documentation before concluding that it is no longer available.
Which NHIS variables have been discontinued with the release of 2025 data?
In our initial data processing of the 2025 NHIS sample, released at the end of August 2026, we observed that multiple long-standing items were absent. Below, we describe the long-standing items that we noticed were absent as of this writing.
Food Security
Notably, there were no food security items included with the 2025 data, including an additional measure on SNAP benefit receipt in the past 30 days. The absence of these measures was an expected discontinuation, documented in an updated footnote in NCHS documentation about NHIS sustaining sponsors, as described in this IPUMS blog post about the broader discontinuation of USDA-sponsored food security items on household surveys.
Immunization
Multiple items from an immunization supplement sponsored by the National Center for Immunization and Respiratory Diseases (NCIRD) were also absent from the 2025 data (refer to Table 1 below), although NCIRD is still identified as a sustaining NHIS sponsor and sponsored several continuing immunization measures. The discontinuation of some immunization measures could simply reflect the removal of items that have declined in importance with shifts in the landscape of vaccination practice, such as questions about the number of COVID-19 vaccine doses or brand of COVID-19 vaccine first received. Measures of ever having received a COVID-19 vaccination continue. Similarly, we observed removal of items asking about a specific brand name of shingles vaccine (Zostavax) but the retention of an “ever received” shingles vaccine variable.
A handful of other items continue to be of substantial public health importance (Callahan et al. 2021; Cambou et al. 2021; Meghani et al. 2023; Evensen-Martinez et al. 2026; Gibson and Greene 2020, Guardiano et al. 2024; Srinivasan, et al. 2021; Sulley et al. 2025) and their exclusion from the 2025 data was unexpected. Five long-running immunization items – three items about flu shots during pregnancy – PREGFLUYR_A (IPUMS NHIS variable PREGFLUYR), FLUSHPG1 (PREGFLUSH), and FLUSHPG2 (PREGFLUSH) – and two items about whether sample adults worked or volunteered in a health care setting – WRKHLTH (WORKVOLHCSET) and WRKDIR (WORKVOLHCPAT and WORKVOLMED) – were not included in the 2025 data.
Table 1. Long-Running Immunization Supplement Items Sponsored by the National Center for Immunization and Respiratory Diseases (NCIRD) Absent from the 2025 NHIS Questionnaire
| NHIS name1 | IPUMS NHIS name | Variable Label | Year Introduced |
|---|---|---|---|
| PREGFLUYR_A | PREGFLUYR | Were you pregnant any time [during the last flu season]? | 2019 |
| FLUSHPG1 | PREGFLUSH | Did you get a flu vaccination before or during your current pregnancy? | 2012 |
| FLUSHPG2 | PREGFLUSH | Earlier you said you were pregnant sometime [during the last flu season]. Did you get a flu vaccination before, during, or after your pregnancy? | 2012 |
| SHTCVD19NM | CVDSHTNUM | How many COVID-19 vaccinations have you received? | 2021 |
| SHOTTYPE | CVDSHTTYPE1 | [For your first shot, which] brand of COVID-19 vaccine did you receive? | 2022 |
| SHINGYEARP_A | SHOTSHNGYR | What year did you get your most recent shingles vaccine? | 2022 |
| SHINGWHEN1_A | SHOTSHNGC | Was [your last shingles vaccine] before 2017? | 2022 |
| SHINGRIX3_A | SHOTSGRXEV | Have you ever had any Shingrix® shots? | 2018 |
| SHINGRIXN3_A | SHOTSGRXNO | How many Shingrix® shots have you ever had? | 2018 |
| SHINGRIXFS_A | SHOTSGRX21 | Was your most recent Shingrix® shot in [SHINGYEARP_A] your first or second Shingrix® shot? | 2022 |
| WRKHLTH | WORKVOLHCSET | Do you currently volunteer or work in a hospital, medical clinic, doctor’s office, dentist’s office, nursing home or some other health-care facility? | 2009 |
| WRKDIR | WORKVOLHCPAT, WORKVOLMED | Do you provide direct patient care as part of your routine work? | 2009 |
The immunization items that were absent from the 2025 questionnaire are not part of NHIS “core” content, meaning that they are not paid for by NCHS. Instead, they are part of an immunization supplement sponsored by NCIRD. We would expect questionnaire content to change from year-to-year to better meet public health surveillance needs. NHIS questionnaire content may also change from year-to-year because of real funding constraints and shifting sponsor priorities. The rationale for the modification or removal of content is not always clear. And it is, of course, always possible that these measures will reappear on the questionnaire in the future.
Newly Announced Proposed Changes to the NHIS Questionnaire
On August 20, 2026, NCHS published a Federal Register notice asking for public comment on proposed changes to the NHIS questionnaire – the deadline for comment is October 20. Note that the proposed changes to the NHIS questionnaire described in the Federal Register notice are distinct from the changes to the 2025 NHIS content discussed above. IPUMS NHIS is reviewing and summarizing the proposed changes and highlighting helpful resources for responding to the Federal Register notice; we will update our summary document with additional information from other organizations, data users, and our own assessments. Note that the IPUMS NHIS website provides information at a glance on the availability of specific measures, organized by topic, and makes it easy to examine changes in question phrasing over time.
References
Callahan, Alice G., Victoria H. Coleman-Cowger, Jay Schulkin, and Michael L. Power. “Racial disparities in influenza immunization during pregnancy in the United States: a narrative review of the evidence for disparities and potential interventions.” Vaccine 39, no. 35 (2021): 4938-4948.
Cambou, Mary Catherine, Timothy P. Copeland, Karin Nielsen-Saines, and James Macinko. “Insurance status predicts self-reported influenza vaccine coverage among pregnant women in the United States: a cross-sectional analysis of the National Health Interview Study Data from 2012 to 2018.” Vaccine 39, no. 15 (2021): 2068-2073. https://doi.org/10.1016/j.vaccine.2021.07.028
Evensen-Martinez, Maison, Meave Phipps, Natalia Correa, and Isain Zapata. “Wellness assessment of United States healthcare provider and healthcare-support personnel using NHIS (National Health Interview Survey).” Public Health 253 (2026): 106213.
Gibson, Diane M., and Jessica Greene. “Risk for Severe COVID-19 Illness Among Health Care Workers Who Work Directly with Patients: Gibson et al.” Journal of General Internal Medicine 35, no. 9 (2020): 2804-2806.
Guardiano, Megan, Timothy A. Matthews, Wendie Robbins, and Jian Li. “Comparison of Working Conditions Between Immigrant and Non-immigrant Healthcare Workers in the United States: Evidence From the National Health Interview Survey.” Safety and Health at Work 15, no. 4 (2024): 491-495.
Meghani, Mehreen, Hilda Razzaghi, Katherine E. Kahn, Mei-Chuan Hung, Anup Srivastav, Peng-jun Lu, Sascha Ellington et al. “Surveillance systems for monitoring vaccination coverage with vaccines recommended for pregnant women, United States.” Journal of Women’s Health 32, no. 3 (2023): 260-270.
Srinivasan, Mithuna, Xi Cen, Brandy Farrar, Jennifer A. Pooler, and Talia Fish. “Food Insecurity Among Health Care Workers In The US: Study examines food insecurity among health care workers in the United States.” Health Affairs 40, no. 9 (2021): 1449-1456.
Sulley, Saanie, David Adzrago, Cameron K. Ormiston, and Faustine Williams. “Mental health outcomes among US healthcare workers before, during, and after the 2019 global respiratory pandemic: A population-based study.” Journal of affective disorders (2025): 120342.