Concurrent Administration of COVID-19 and Influenza Vaccines Enhances Spike-Specific Antibody Responses

Abstract

Abstract Background The bivalent COVID-19 mRNA boosters became available in fall 2022 and were recommended alongside the seasonal influenza vaccine. However, the immunogenicity of concurrent vs separate administration of these vaccines remains unclear. Methods Here, we analyzed antibody responses in health care workers who received the bivalent COVID-19 booster and the influenza vaccine on the same day or on different days through systems serology. Antibody-binding and functional responses were characterized at peak responses and after 6 months following vaccination. Results IgG1 and neutralization responses to SARS-CoV-2 XBB.1.5 were higher at peak and after 6 months following concurrent administration as compared with separate administration of the COVID-19 and influenza vaccines. While similar results were not observed for influenza responses, no interference was noted with concurrent administration. Conclusions These data suggest that concurrent administration of these vaccines may yield higher and more durable SARS-CoV-2 neutralizing antibody responses while maintaining responses against influenza.