Background: High-dose influenza vaccine (Fluzone High-Dose, Sanofi) is an alternative to other standard-dose influenza vaccines, and was recently preferentially recommended for adults aged 65 or older in the United States (US) for the 2022-2023 influenza season. Little is known about how racial disparities in type of influenza vaccine received vary geographically.
Objectives: To assess for racial disparities in high-dose influenza vaccine receipt among Black and White US Traditional Medicare beneficiaries vaccinated against influenza within states and hospital referral regions. We hypothesized that racial disparities would exist and would vary substantially across states and hospital referral regions.
Methods: This was a nationally representative retrospective cohort study conducted with over 11.7 million community-dwelling Black and White adults aged ≥65 years enrolled in Traditional Medicare and vaccinated against influenza during the 2015-16 influenza season. A 100% sample of Medicare Part B carrier and outpatient files was used to obtain information on influenza vaccination and type of vaccine received (high-dose versus standard-dose). The comparison of interest was marginalized versus privileged racial group measured as Black versus White race. Direct standardization was used to calculate age- and sex-standardized estimates of high-dose influenza vaccine receipt nationally as well as at the state and hospital referral region level, and disparities were measured as differences in the proportions of Black and White beneficiaries who received high-dose influenza vaccines.
Results: The national disparity in high-dose influenza vaccine receipt was 12.8 percentage points. The median disparity was 10.7 percentage points among states (minimum, maximum: 2.9, 25.6; n=30 states), and 11.6 percentage points among hospital referral regions (minimum, maximum: 0.4, 24.7; n=54 hospital referral regions). The District of Columbia had the largest disparity (25.6 percentage points; 95% confidence limits (CLs), 24.1, 27.1) and was followed by the hospital referral region associated with Chicago, Illinois (24.7 percentage points; 95% CLs, 23.9, 25.6).
Conclusions: Vaccination with high-dose influenza vaccines was less common among Black beneficiaries compared to White beneficiaries in every state and hospital referral region in the analysis. There was substantial geographic variation in disparities, which ranged from small disparities (less than 1 percentage point) to disparities in excess of 25 percentage points. These findings highlight the need for localized interventions and policies, which may have the largest impact on the elimination of such inequities in vaccination.
