Early Estimates of Bivalent mRNA Vaccine Effectiveness in Preventing COVID-19–Associated Hospitalization Among Immunocompetent Adults Aged ≥65 Years — IVY Network, 18 States, September 8–November 30, 2022

Authors: Diya Surie, Jennifer DeCuir, Yuwei Zhu, Manjusha Gaglani, Adit A. Ginde, David J. Douin, H. Keipp Talbot, Jonathan D. Casey, Nicholas M. Mohr, Anne Zepeski, Tresa McNeal, Shekhar Ghamande, Kevin W. Gibbs, D. Clark Files, David N. Hager, Harith Ali, Leyla Taghizadeh, Michelle N. Gong, Amira Mohamed, Nicholas J. Johnson, Jay S. Steingrub, Ithan D. Peltan, Samuel M. Brown, Emily T. Martin, Akram Khan, William S. Bender, Abhijit Duggal, Jennifer G. Wilson, Nida Qadir, Steven Y. Chang, Christopher Mallow, Jennie H. Kwon, Matthew C. Exline, Adam S. Lauring, Nathan I. Shapiro, Cristie Columbus, Natasha Halasa, James D. Chappell, Carlos G. Grijalva, Todd W. Rice, William B. Stubblefield, Adrienne Baughman, Kelsey N. Womack, Jillian P. Rhoads, Kimberly W. Hart, Sydney A. Swan, Nathaniel M. Lewis, Meredith McMorrow, Wesley H. Self, IVY Network - MMWR Morbidity and Mortality Weekly Report 2022 cited by 117

assessed effectiveness of a bivalent booster dose received after ≥2 doses of monovalent mRNA vaccine against COVID-19-associated hospitalization among immunocompetent adults aged ≥65 years. When compared with unvaccinated persons, VE of a bivalent booster dose received ≥7 days before illness onset (median = 29 days) against COVID-19-associated hospitalization was 84%. Compared with persons who received ≥2 monovalent-only mRNA vaccine doses, relative VE of a bivalent booster dose was 73%. These early findings show that a bivalent booster dose provided strong protection against COVID-19-associated hospitalization in older adults and additional protection among persons with previous monovalent-only mRNA vaccination. All eligible persons, especially adults aged ≥65 years, should receive a bivalent booster dose to maximize protection against COVID-19 hospitalization this winter season. Additional strategies to prevent respiratory illness, such as masking in indoor public spaces, should also be considered, especially in areas where COVID-19 community levels are high (4,5).