Shingles vaccination in Medicare Part D and commercial enrollees after the inflation reduction act.

The impact of the 2022 United States Inflation Reduction Act policy on the recombinant zoster vaccine uptake in Medicare Part D enrollees remains unclear after cost-sharing was eliminated for vaccines recommended by the Advisory Committee on Immunization Practices. We implemented a difference-in-difference linear model with individuals aged 50 years and older from November 2021 to December 2024 from the Optum Labs Data Warehouse, a de-identified claims database, to compare the uptake in commercial and Medicare Part D enrollees following the policy change. Additionally, out-of-pocket costs were summarized. Eliminating cost-sharing significantly increased recombinant zoster vaccine uptake among Medicare Part D beneficiaries. The estimated increase in vaccinations attributable to the policy change was 26.3 per 10,000 Medicare Part D enrollees (95 % CI: 11.2-41.4). The median out-of-pocket cost was $45.00 before and $0 after the policy change. Vaccine coverage remains insufficient, highlighting the need for targeted strategies to improve vaccination rates.