Area-Level Disparities in Pneumococcal Vaccination Among Publicly Insured US Adults: 2016-2019

Understanding pneumococcal vaccine uptake across county-level social vulnerability is important for identifying geographic disparities and informing strategies to increase vaccine uptake and reduce the incidence of pneumococcal disease (PD). Using a retrospective cohort design, we characterized differences in vaccine uptake among publicly insured US adults, comparing vaccination rates among beneficiaries in counties with high versus low social vulnerability.

We assessed uptake and disease risk using claims for Medicare (aged ≥65 y; 2016-2019) and Medicaid (low income or disabled; 2017-2019) beneficiaries. We measured county-level social vulnerability using the 2021 Minority Health Social Vulnerability Index (overall score and 6 theme scores).

Of the 56.9 million Medicare beneficiaries analyzed, 36.9% received a pneumococcal vaccine, as did 7.6% of the 8.6 million Medicaid beneficiaries. Vaccine uptake was significantly lower in counties with the highest versus lowest social vulnerability (34.8% vs 38.6% among Medicare beneficiaries, P < .001 and 7.3% vs 7.9% among Medicaid beneficiaries, P < .001). Disparities were most pronounced when vulnerability was based on the socioeconomic status theme in the Medicare cohort and on the health care infrastructure and access theme in the Medicaid cohort. The overall pattern was reversed (with higher uptake in the most vulnerable counties) when vulnerability was based on the minority status and language theme among Medicaid beneficiaries at high risk for PD. Controlling for beneficiary characteristics (age group, sex, disease risk status, race and ethnicity, and urbanicity) strengthened the association between vulnerability and uptake.

These findings suggest that county- and individual-level factors are associated with disparities in pneumococcal vaccine uptake and underscore the need for tailored clinical, community, and policy strategies to boost pneumococcal vaccine uptake in socially vulnerable populations.