Pfizer and BioNTech Combination Vaccine Candidate Fails to Meet All Immunogenicity Goals

Pfizer Inc. and BioNTech SE announced top-line results from their late-stage clinical trial for a combination mRNA vaccine candidate targeting both influenza and COVID-19. The Phase 3 study involved over 8,000 adults and aimed to evaluate the vaccine's safety, tolerability, and immunogenicity.

The combination candidate, combining Pfizer's mRNA-based influenza vaccine with BioNTech's licensed COVID-19 vaccine, successfully met one of its two primary immunogenicity objectives. Specifically, it demonstrated comparable antibody responses against SARS-CoV-2 when compared to a separate COVID-19 vaccine. The vaccine also elicited strong responses against the influenza A strain, exceeding levels seen with some comparator vaccines.

However, the candidate fell short of its goal regarding the influenza B strain. The vaccine did not meet the non-inferiority objective for antibody responses against influenza B, despite showing a trend of higher responses against influenza A. The companies stated they are evaluating potential modifications to the candidate to improve its efficacy against influenza B and plan to discuss the next steps with regulatory authorities.

In parallel, Pfizer also reported encouraging data from a separate Phase 2 trial of its standalone mRNA-based influenza vaccine. This separate vaccine candidate showed robust immunogenicity against all three influenza strains compared to a standard-of-care influenza vaccine.

The companies maintain that combination vaccines represent an efficient approach to reducing the burden of respiratory diseases and are committed to their ongoing development. No safety signals have been identified for the combination vaccine candidate in the ongoing safety data review.