Pfizer and BioNTech Update mRNA Combination Vaccine Program for Flu and COVID-19 in Adults 18-64

Pfizer Inc. and BioNTech SE have reported promising outcomes from their Phase 3 clinical trial assessing a combined mRNA vaccine for influenza and COVID-19 in healthy adults aged 18 to 64. The combination vaccine merges Pfizer's mRNA-based influenza vaccine candidate with the currently licensed COVID-19 vaccine from the two companies. This trial primarily aimed to evaluate the immunogenicity against both SARS-CoV-2 and influenza A and B, achieving one of these primary immunogenicity objectives. In a separate Phase 2 trial, a trivalent influenza mRNA standalone vaccine showed strong immune responses in the same age group. Further modifications to enhance the combination vaccine's efficacy against influenza B are under consideration, with the companies planning to discuss subsequent steps with health authorities.

The Phase 3 study, a randomized, observer-blinded trial, included over 8,000 participants aged 18 to 64 to assess the safety, tolerability, and immunogenicity of a single dose of the combination vaccine. The combination vaccine was compared to a licensed influenza vaccine and their licensed COVID-19 vaccine administered concurrently. The primary goal was to confirm that the antibody responses to both influenza (measured by hemagglutination inhibition) and SARS-CoV-2 (measured by neutralizing titer) were non-inferior to the standard care. The combination vaccine elicited robust responses against influenza A, though it showed lower geometric mean titers and seroconversion for influenza B. The responses against SARS-CoV-2 were comparable to the companies' licensed COVID-19 vaccine. Importantly, no safety concerns have been noted so far in the ongoing safety review. Participants who received both the licensed influenza and COVID-19 vaccines together also showed strong immune responses to both viruses, with no safety issues identified.

Dr. Annaliesa Anderson, Senior Vice President and Head of Vaccine Research and Development at Pfizer, expressed optimism about the combination vaccine's performance against influenza A and its potential to reduce the burden of respiratory diseases through efficient combination vaccines. Prof. Ugur Sahin, CEO and Co-founder of BioNTech, emphasized the importance of developing combination vaccines for broader protection against respiratory illnesses. He highlighted the valuable insights gained from this trial in guiding the future development of their combined vaccine program against influenza and COVID-19.

Furthermore, Pfizer's Phase 2 trial on second-generation influenza vaccine candidates began earlier this year with 450 participants aged 18 to 64. This trial aimed to evaluate the immunogenicity of investigational mRNA-based influenza vaccines compared to FDA-approved influenza vaccines. Positive top-line results from Pfizer's first-generation quadrivalent mRNA vaccine had previously been reported, demonstrating significant efficacy in the 18-64 age group. However, the primary endpoints were not met for adults aged 65 and older. Building on these results, Pfizer developed second-generation candidates to improve immune response and breadth of protection, aligning with updated recommendations from the World Health Organization and the FDA’s Vaccines and Related Biological Products Advisory Committee. These second-generation formulations showed strong responses to both influenza A and B, with no safety concerns reported. Data on the older age group from this Phase 2 trial will be available later.

Pfizer continues to evaluate its influenza vaccine program and plans to discuss future steps with health authorities. Influenza remains a significant public health issue, with considerable hospitalizations, deaths, and economic losses annually in the U.S. The flexibility and rapid manufacturing capabilities of mRNA technology hold promise for better strain matching in future vaccines, potentially enhancing protection against influenza in upcoming seasons.