Effectiveness of COVID-19 bivalent vaccination against SARS-CoV-2 infection among residents of US nursing homes, November 2022 - March 2023.

BACKGROUND

Residents of nursing homes remain an epidemiologically important population for COVID-19 prevention efforts, including vaccination. We aim to understand effectiveness of bivalent vaccination for preventing SARS-CoV-2 infections in this population.

METHODS

We used a retrospective cohort of nursing home residents from November 1, 2022, through March 31, 2023, to identify new SARS-CoV-2 infections. A Cox proportional hazards model was used to estimate hazard ratios comparing residents with a bivalent vaccination compared with residents not up to date with vaccination recommendations. Vaccine effectiveness was estimated as (1 - Hazard Ratio) * 100.

RESULTS

Among 6,916 residents residing in 76 nursing homes included in our cohort, 3,211 (46%) received a bivalent vaccine 7 or more days prior to censoring. Adjusted vaccine effectiveness against laboratory confirmed SARS-CoV-2 infection comparing receipt of a bivalent vaccine versus not up to date vaccine status was 29% (95% Confidence interval 18% to 39%). Vaccine effectiveness for receipt of a bivalent vaccine against residents who were unvaccinated or vaccinated more than a year prior was 32% (95% CI: 20% to 42%,) and was 25% compared with residents who were vaccinated with a monovalent vaccine in the past 61-365 days (95% CI:10% to 37%).

CONCLUSIONS

Bivalent COVID-19 vaccines provided additional protection against SARS-CoV-2 infections in nursing home residents during our study time-period, compared to both no vaccination or vaccination more than a year ago and monovalent vaccination 60 - 365 days prior. Ensuring nursing home residents stay up to date with vaccine recommendations remains a critical tool for COVID-19 prevention efforts.

Informations de copyright

Copyright © 2024. Published by Elsevier Ltd.

Déclaration de conflit d'intérêts

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.