Safety and immunogenicity of a 20-valent pneumococcal conjugate vaccine coadministered with quadrivalent influenza vaccine: A phase 3 randomized trial

Introduction: Older adults are at increased risk of adverse outcomes from pneumococcal disease and influenza infections. Vaccination is an established strategy for preventing both illnesses. This study evaluated coadministration of 20-valent pneumococcal conjugate vaccine (PCV20) and an adjuvanted quadrivalent inactivated influenza vaccine (QIV).

Methods: This phase 3, randomized, double-blind, multicenter study included 1796 US adults ≥ 65 years of age randomized 1:1 to receive either PCV20 and QIV followed 1 month later by saline (Coadministration group) or QIV and saline followed 1 month later by PCV20 (Separate Administration group). Primary immunogenicity objectives were to show noninferiority of PCV20 and QIV coadministration compared with separate administration of either vaccine based on serotype-specific opsonophagocytic activity (OPA) titers for PCV20 and strain-specific hemagglutination inhibition assay (HAI) titers for QIV. Safety endpoints included local reactions, systemic events, and adverse events (AEs).

Results: Noninferiority for pneumococcal and influenza antibody responses (lower bound 95 % CI of the OPA and HAI geometric mean ratios of > 0.5 and > 0.67, respectively) was shown for the Coadministration group compared with the Separate Administration group for all 20 pneumococcal serotypes and all 4 influenza vaccine strains. Local reactions and systemic events were mostly mild or moderate in severity across groups; injection site pain was the most frequent local reaction, and fatigue was the most frequent systemic event. Mild and moderate fatigue were reported more frequently after PCV20 and QIV coadministration compared with separate administration (mild, 20.0 % vs 10.8 %-12.6 %; moderate, 12.3 % vs 8.4 %-9.6 %); this was not considered clinically significant. AE reporting rates were similar across groups, and no serious AEs were considered vaccination-related.

Conclusions: Immune responses after coadministration of PCV20 and QIV were noninferior to separate administration of either vaccine. The PCV20 safety profile was similar when given together with or after QIV. These findings support PCV20 and QIV coadministration.

Trial registration: ClinicalTrials.gov, NCT04526574.