This retrospective cohort study evaluated the comparative vaccine effectiveness (cVE) of licensed standard-dose cell-based versus egg-based influenza vaccines in preventing influenza hospitalization among adults 18-64 years during the 2022-2023 season. The cohort included eligible Kaiser Permanente Southern California members who received ≥ 1 dose of influenza vaccine (n = 848,334). The adjusted cVE against influenza hospitalization was -10.1% (95% CI: -49.8%, 37.8%) in the 18- to 49-year-old cohort. In the 50- to 64-year-old cohort, the adjusted cVE was 14.9% (-33.8%, 52.1%). Cell-based and egg-based influenza vaccines conferred comparable protection against influenza hospitalization in adults 18-64 years of age in the 2022-2023 season.
Keywords: Influenza; epidemiology; influenza vaccine; vaccine effectiveness.
© 2024 The Author(s). Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.