Influenza Vaccination Coverage, Adults

• The National Immunization Survey-Adult COVID Module (NIS-ACM) was launched in April 2021 among adults 18 years and older. The survey is used to monitor COVID-19 vaccination uptake and confidence in vaccination among adults and also includes questions about influenza vaccination.
• Vaccination coverage estimates for the current season are based on all interviews through the current week and represent approximately the cumulative percent vaccinated by mid-week. Each week, estimates for prior weeks are recalculated using the additional interviews conducted that week (combined with all previous interviews).
• The NIS-ACM adult flu vaccination coverage estimates for prior season(s) are based on interviews conducted during each approximate monthly analysis period and can increase or decrease over time due to random sampling variation. This will happen more frequently for groups with smaller sample sizes. These prior season estimates were capped at February and April, respectively; these are the months when the national overall coverage estimate was the highest. This makes the remainder of the national overall coverage estimates non-decreasing.
• Confidence Intervals (CI) describe the level of uncertainty around an estimate because a sample was taken. 95% CIs represent the range of values that would result if the data collection had been repeated many times. For a 95% confidence interval, if the sampling method is repeated many times, the true value would fall within this interval at least 95% of the time. Wider CIs reflect larger random error in estimates resulting from survey sampling.
• Estimates from the NIS-ACM may differ from estimates based on other data sources, and in addition to random error related to taking a sample, are subject to errors resulting from incomplete sample frame (exclusion of households without cell phones), selection bias (survey respondents may be more likely to be vaccinated than non-respondents), and errors in self or parental reported vaccination status. Estimates are weighted to selected sociodemographic characteristics of the U.S. population to reduce possible bias from incomplete sample frame and selection bias.
• Figure 4A. Influenza Vaccination Coverage, Overall, by Selected Demographics, Jurisdiction, and 2021-22 through 2023-24, Adults 18 years and Older, United States,^*‡†±. Data Source: National Immunization Survey-Adult COVID Module.
• Figure 4B. Overall Influenza Vaccination Coverage Map and Comparison between 2023-24 and Prior Two Seasons^*‡†, Adults 18 years and Older, United States^*‡. Data Source: National Immunization Survey-Adult COVID Module.
• Figure 4C. Differences in Influenza Vaccination Coverage by Selected Demographics, 2023-24, and 2023-24 Compared with 2022-23, Adults 18 years and Older, United States^{*‡†^±}. Data Source: National Immunization Survey-Adult COVID Module.
• Figure 4D. Weekly Influenza Vaccination Status and Intent for Vaccination, Overall, by Selected Demographics, and Jurisdiction, Adults 18 years and Older, 2023-24, United States^{*‡†^±}. Data Source: National Immunization Survey-Adult COVID Module.

^* National estimates include 50 states, Washington D.C., Puerto Rico, and when available, U.S. Virgin Islands and/or Guam. Office of Intergovernmental and External Affairs hosts 10 Regional Offices that directly serve state and local organizations; information about Regions and which states are included in each region is available.

^‡ Weekly 2023-24 estimates are not reported if total sample size to date is less than 30 or sample size <5 for current week. Monthly 2022-23 and 2021-22 estimates are not reported if they do not meet the NCHS standards of reliability [1.5 MB, 22 pages]. 

^†The current season’s weekly estimates as of approximately mid-month can be compared with the mid-month estimates from the prior season. Given this, for Figure 4B, data will appear in the ‘Difference’ map on the right side, only when the current week corresponds to the mid-month estimate (e.g., when current week selected is ‘October 14, 2023, November 11, 2023, and so on); the same applies to Figure 4C, Table 2. The NIS-ACM adult data shown for the week ending March 31, 2024 includes the additional day of data collected on March 31, 2024, due to questionnaire changes that went into effect April 1, 2024.

^{^}Estimates for vaccination intent are based on interviews conducted that week and are adjusted to the cumulative vaccination coverage estimate through that week. Estimates of intent for vaccination are not shown for a given week if sample size for that week is <30.

±The ‘Multiple or Other Races, Non-Hispanic’ category includes non-Hispanic persons who selected multiple races or a race other than American Indian/Alaskan Native, Asian, Black, Native Hawaiian or other Pacific Islander, or White.