Safety and immunogenicity of a quadrivalent inactivated influenza vaccine in adults.

•Phase 3 trial of quadrivalent (QIV) and trivalent (TIV) influenza vaccine in adults.•Antibody responses to QIV were non-inferior to TIV responses for matched strains.•Antibody responses to QIV were superior to those to TIV with an unmatched B strain.•The QIV was well tolerated without any safety concerns.•The QIV could help address an unmet need due to mismatched B strains.