Vaccine Efficacy Against Influenza Demonstrated through Humoral and Cellular Immune Response

Strategic Insights -

A recent cluster randomized trial conducted during the 2008-2009 season in Canada has provided insight into the mechanism behind influenza vaccination. The study, led by researchers at McMaster University, measured the proportion of protection against influenza mediated through antibodies and other immune mechanisms. The findings suggest that influenza vaccination may protect through both the humoral immune response, which is mediated by antibodies, and the cellular immune response.

Key Takeaways:

  • Vaccine efficacy against influenza A (H3N2) was 63%, while against influenza B it was 28%.
  • The study found that the protective effect for vaccination against influenza A was largely mediated by antibodies, but this was not the case for influenza B, where most of the vaccine effectiveness was likely due to other immune mechanisms.
  • The study used a cluster randomized trial conducted in 46 Hutterite colonies in Canada, involving 617 children aged 3-15 years who were vaccinated with either inactivated trivalent influenza vaccine or hepatitis A vaccine.
  • Inverse probability weighting was used to calculate the indirect and direct effect of vaccination against influenza A/H3N2 and influenza B, using hemagglutination inhibition (HAI) titers.
  • The study also used microneutralization analysis to confirm that the protective effect for vaccination against influenza A was entirely mediated by antibodies.

Statistics:

  • 63% vaccine efficacy against influenza A (H3N2)
  • 28% vaccine efficacy against influenza B
  • 617 children involved in the study, aged 3-15 years
  • 46 Hutterite colonies in Canada used in the cluster randomized trial
  • 488 children used in the microneutralization analysis

Sources:

  • The role of influenza Hemagglutination-Inhibition antibody as a vaccine mediator in children. Vaccine, 2024:126122.
  • NewsRx. McMaster University Reports Findings in Vaccine Efficacy (The role of influenza Hemagglutination-Inhibition antibody as a vaccine mediator in children). Pediatrics Week. August 17, 2024; p 291.