Annual immunizations against SARS-CoV-2 and influenza viruses are crucial for public health, addressing the evolving nature of these viruses. Aiming to enhance influenza vaccines for older adults, researchers have focused on eliciting broad immune responses against different flu strains, particularly H3N2, while avoiding antigenic changes related to egg adaptation. Findings from the study were presented as research at the ESCMID Global Congress.
In the study conducted in Australia and New Zealand, involving 1579 participants aged 50–80 years, researchers investigated the efficacy of a saponin-adjuvanted recombinant quadrivalent hemagglutinin (HA) nanoparticle influenza vaccine (qNIV) and a COVID-19 and influenza combination (CIC) vaccine. The CIC vaccine comprised recombinant SARS-CoV-2 Spike (rS), qNIV, and Matrix-M adjuvant.
Participants were randomly assigned to receive one intramuscular dose of vaccine from various formulations. Pre- and post-vaccination assessments measured anti-spike IgG, SARS-CoV-2 neutralizing antibodies, influenza HAI antibodies, and CD4+ T-cell responses. Reactogenicity was monitored for seven days post-vaccination, with additional safety outcomes assessed through Day 21.
Results showed that qNIV elicited significantly higher HAI responses against influenza A strains than standard influenza vaccines. The CIC vaccine demonstrated evidence of antigen interference but achieved comparable immune responses to the rS vaccine and licensed influenza vaccines. Adverse events associated with CIC and qNIV were like those observed with standard influenza vaccines.