A Phase III randomised trial of the immunogenicity and safety of quadrivalent versus trivalent inactivated subunit influenza vaccine in adult and elderly subjects, assessing both anti-haemagglutinin and virus neutralisation antibody responses

QIV was non-inferior in immunogenicity to TIV for matched strains and superior to the alternate-lineage B-strains in TIV. Safety and tolerability profiles of QIV and TIV were comparable.