October 21, 2022
Effectiveness of COVID-19 mRNA Vaccines Against COVID-19-Associated Hospitalization Among Immunocompetent Adults During BA.1/BA.2 and BA.4/BA.5 Predominant Periods of SARS-CoV-2 Omicron Variant in the United States
CDC published an MMWR on effectiveness of monovalent mRNA vaccines against COVID-19–associated hospitalization among immunocompetent adults during BA.1/BA.2 and BA.4/BA.5 predominant periods of SARS-CoV-2 Omicron variant in 18 states from December 2021 to August 2022. Monovalent mRNA vaccine effectiveness (VE) against COVID-19–associated hospitalization wanes over time; less is known about durability of protection during the SARS-CoV-2 Omicron BA.4/BA.5–predominant period. Three-dose monovalent mRNA VE estimates against COVID-19–associated hospitalization decreased with time since vaccination. Three-dose VE during the BA.1/BA.2 and BA.4/BA.5 periods was 79% and 60%, respectively, during the initial 120 days after the third dose and decreased to 41% and 29%, respectively, after 120 days from vaccination. Eligible adults aged ≥18 years should receive an updated bivalent COVID-19 mRNA vaccine to maximize protection against BA.4/BA.5 lineages and to prevent COVID-19–associated hospitalization.