Codes and Frequencies
For sample adults and sample children, VACFLU12M reports whether or not the person had a flu vaccine in the past 12 months.
See the Comparability Tab for additional information about changes to the universe and construction of this variable over time as well as information about seasonal flu versus H1N1 flu vaccinations in 2009-2011.
In 2005-2015 for sample adults, and 2005-August 10, 2010 for sample children, the survey asked whether sample persons had a flu shot vaccine (VACFLUSH12M), and also asked if they had a flu nasal spray vaccine (VACFLUSP12M) in the past 12 months. For either mode of vaccination the sample person reported receiving in the past 12 months, they were asked for the month (VACFLUSHMO/VACFLUSPMO) and year (VACFLUSHYR/VACFLUSPYR) of their most recent vaccine by this mode.
For sample children surveyed after August 10, 2010 in the 2010 NHIS sample and sample adults beginning in the 2016 NHIS sample, a streamlined set of questions about flu vaccines was asked. Sample persons were asked if they had received a flu vaccine in the past 12 months (VACFLU12M), then asked for the month (VACFLUMO) and year (VACFLUYR) of their most recent vaccine, as well as the mode of their most recent flu vaccine (choosing between a shot or nasal spray) (VACFLUMODE), available through 2018). Sample children were asked if they had more than one vaccination in the past year (VACFLUNUM) and could also report the mode (VAC2FLUMODE, available through 2018), month (VAC2FLUMO), and year (VAC2FLUYR) of their second most recent flu vaccination.
The 2010 NHIS sample includes variables associated with both versions of the flu vaccine questions. The original NHIS files do not offer the variables associated with VACFLU12M for sample children in 2005-2009, or for sample adults in 2005-2015. IPUMS NHIS has utilized the vaccine-mode specific information to replicate VACFLU12M for sample children surveyed after August 10, 2010 and for sample adults in 2016 forward. Sample persons who supplied a non-valid response for one vaccine mode and "no" to the other, are assigned the non-valid response value for VACFLU12M.
Seasonal versus H1N1 flu vaccines
Generally, the survey question associated with this variable asks about seasonal flu vaccines and specifies that they are usually given in the fall to protect against influenza for the flu season. The 2009-2010 seasonal flu vaccine did not include protection against H1N1, as the H1N1 vaccine was developed later; from October 2009-August 10, 2010, the survey question explicitly clarifies that sample persons are NOT to include H1N1 or "swine" flu vaccines when answering this question. In January 2010, the NHIS added distinct supplemental questions about H1N1 flu vaccinations (VACH1N1GOT). Beginning on August 11, 2010 onward, the survey question clarifies that the sample person's most recent flu vaccination could have been the new 2010-2011 seasonal flu vaccine (which included protection against H1N1) or an H1N1 vaccine, but does not clarify which vaccination the sample person received.
Questionnaire changes introduced in 2019 may affect comparability
The NHIS questionnaire was substantially redesigned in 2019 to introduce a different data collection structure and new content. These changes may affect comparability with earlier years. For more information on changes in terminology, universes, and data collection methods beginning in 2019, please see the user note.
- 2005-2018: Sample adults and sample children.
- 2019-2021: Sample adults age 18+ and sample children ages 0-17.
- 2010-2021 : SAMPWEIGHT