Pfizer, BioNTech give update on mRNA-based combination vaccine programme

Pfizer announced top-line results from their Phase 3 clinical trial to evaluate the companies’ combined mRNA vaccine candidate against influenza and COVID-19 in healthy individuals 18-64 years of age. The combination candidate consists of Pfizer’s mRNA-based influenza vaccine candidate with the companies’ licensed COVID-19 vaccine. 

The Phase 3 trial measured two primary immunogenicity objectives (immunogenicity against SARS-CoV-2 as well as immunogenicity against influenza A and B), of which one was met. In a separate Phase 2 trial, Pfizer evaluated trivalent (“tIRV”) influenza mRNA standalone vaccine candidates which demonstrated robust immunogenicity in individuals 18-64 years of age. The companies are evaluating adjustments to the combination vaccine candidate aimed at improving immune responses against influenza B and will discuss the next steps with health authorities.

Update on Phase 3 Pfizer and BioNTech combination vaccine trial 

The Phase 3 randomised, observer-blinded study enrolled more than 8,000 adults 18-64 years of age to evaluate the safety, tolerability, and immunogenicity of a single-dose combination vaccine candidate against influenza and COVID-19. In this clinical trial, the vaccine candidate was compared to a licensed influenza vaccine and the companies’ licensed COVID-19 vaccine given at the same visit. 

The primary immunogenicity objectives were to demonstrate that the antibody responses to influenza (hemagglutination inhibition, “HAI”) and to SARS-CoV-2 (neutralising titer, “NT”) elicited by the combination vaccine candidate were non-inferior to standard of care. Compared to a licensed influenza vaccine, the tIRV formulation was noteworthy for eliciting robust influenza A responses, including a continued trend of higher influenza A responses versus a licensed influenza vaccine, while it showed lower geometric mean titers and seroconversion against the influenza B strain. In addition, the formulation demonstrated comparable responses against SARS-CoV-2 versus the companies’ licensed COVID-19 vaccine. No safety signals with the combination vaccine have been identified in an ongoing safety data review. Participants who received licensed influenza and COVID-19 vaccines with co-administration continued to elicit robust immune responses against both influenza and COVID-19 with no safety signals identified to date.

Update on Pfizer’s Phase 2 second generation Influenza vaccine trial 

Pfizer’s Phase 2 trial to evaluate second-generation candidates against influenza was initiated earlier this year and enrolled 450 participants 18-64 years of age, who were randomised to receive investigational mRNA-based influenza vaccines or influenza vaccines approved by the US FDA. As previously stated, Pfizer announced positive top-line Phase 3 results from its first-generation quadrivalent (qIRV) vaccine candidate which achieved the first and only demonstration of efficacy for an mRNA vaccine in a group of study participants 18-64 years of age. The primary endpoints for this qIRV first-generation candidate were not met in adults aged 65 and older, as statistical non-inferior relative vaccine efficacy (rVE) compared to a licensed influenza vaccine was not met based on the number of cases accrued. 

Pfizer developed second-generation candidates to improve immunogenicity and potential breadth of protection, including new tIRV formulations that matched updated recommendations by WHO and the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC). The tIRV formulations elicited robust influenza A responses and B responses, including a continued trend of higher influenza A responses versus a licensed influenza vaccine. There were no safety signals reported. 

Pfizer will also continue to evaluate its influenza vaccine programme and discuss next steps with health authorities.