Background: Since influenza and respiratory syncytial virus (RSV) carry significant burden in older adults with overlapping seasonality, vaccines for both pathogens would ideally be coadministered in this population. Here we evaluate the immunogenicity and safety of concomitant administration of Ad26.RSV.preF/RSV preF protein and high-dose seasonal influenza vaccine (Fluzone-HD®) in adults ≥65 years old.
Methods: Participants were randomized 1:1 to the Coadministration or Control group. The Coadministration group received concomitant Ad26.RSV.preF/RSV preF protein and Fluzone-HD® on Day 1 and placebo on Day 29, while the Control group received Fluzone-HD® and placebo at Day 1 and Ad26.RSV.preF/RSV preF protein on Day 29. Influenza hemagglutination-inhibiting and RSV preF-binding antibody titers were measured postvaccination and tested for noninferiority between both groups. Safety data were collected throughout the study and analyzed descriptively.
Results: Coadministered Ad26.RSV.preF/RSV preF protein and Fluzone-HD® vaccines induced noninferior immune responses compared to each vaccine administered alone. Seroconversion and seroprotection rates against influenza were similar between groups. Both vaccines remained well tolerated upon concomitant administration.
Conclusions: Coadministration of Ad26.RSV.preF/RSV preF protein and Fluzone-HD® showed an acceptable safety profile and did not hamper the immunogenicity of either vaccine, thus supporting that both vaccines can be concomitantly administered in adults ≥65 years old.
Keywords: Ad26.RSV.preF/RSV preF protein; Fluzone-HD®; coadministration; influenza; noninferiority; respiratory syncytial virus; vaccine.
© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America.