High-Dose vs. Adjuvanted Flu Vaccine for Older Adults

Current U.S. guidelines recommend that adults aged 65 and older receive one of the enhanced influenza vaccines every year: high-dose inactivated influenza vaccine (Fluzone High-Dose), recombinant influenza vaccine (Flublok), or adjuvanted influenza vaccine (Fluad). But these options have never been compared head-to-head in a randomized trial. To address this gap, investigators from Kaiser Permanente Northern California (KPNC) conducted a cluster-randomized trial during the 2023–2024 influenza season, assigning 65 KPNC outpatient facilities to provide adjuvanted or high-dose influenza vaccine on alternating weeks. Older adults presenting for vaccination were then given whichever vaccine was assigned to the clinic that week.