Durability of Bivalent Boosters against Omicron Subvariants
Danyu Y. Lin, Yangjianchen Xu, Yu Gu, Donglin Zeng, Shadia Khan Sunny, Zack Moore · New England Journal of Medicine · 2023
Durability of Bivalent Boosters against Omicron SubvariantsTo the Editor: On September 1, 2022, the Moderna and Pfizer-BioNTech bivalent vaccines against severe acute respiratory syndrome corona virus 2 (SARSCoV2) containing equal amounts of spike messenger RNA from the ancestral and omicron BA.4-BA.5 subvariants replaced their monovalent counterparts as booster doses for persons who are 12 years of age or older in the United States.We previously reported surveil lance data from North Carolina on the effective ness of these two bivalent boosters against coronavirus disease 2019 (Covid19) during the first 3 months after deployment (September 1 to December 8, 2022); the BA.4-BA.5 subvariants were predominant during the first 2.5 months of this period.1 Here, we present two additional months of data that were obtained during a period when the omicron BQ.1-BQ.1.1 and XBB-XBB.1.5subvariants had become predominant to show the durability of protection conferred by these two bivalent boosters against a wider range of clinical outcomes than were included in our pre vious report.The data sources and study design have been described previously, 13 and updated information is provided in the Methods section of the Supple mentary Appendix, available with the full text of this letter at NEJM.org.The current study used data regarding booster doses and clinical out comes from September 1, 2022, to February 10, 2023, for all North Carolina residents who were 12 years of age or older.During this period, a total of 6,306,311 residents were eligible to receive biva lent boosters; of these residents, 1,279,802 received the injections.A total of 19,462 of the 154,581 SARSCoV2 infections, 253 of the 2208 Covid19related hospitalizations, and 79 of the 867 Covid19-related deaths occurred after receipt of the bivalent booster (Table S1 in the Supplemen tary Appendix).We considered four outcome measures: infec tion, severe infection resulting in hospitalization, severe infection resulting in hospitalization or