Pfizer Doses First Patients with an Influenza Vaccine in a Phase 3 Clinical Trial

On September 14, Pfizer announced the dosing of the first patients of a Phase 3 clinical trial testing their new influenza vaccine. Around 25,000 patients will receive the vaccine to test the efficacy, safety, tolerability, and immunogenicity of the quadrivalent modified RNA (modRNA) vaccine. 

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Influenza and Prior Vaccines

Influenza is one of the most common illnesses. From 2010 to 2020, the Center for Disease Control (CDC) estimated that 9 million – 41 million virus cases occurred annually. The viral infection attacks a patient’s respiratory system, resulting in a persistent cough, fever, and muscle aches, among other symptoms.

Though a vaccine for the flu released to the public as far back as 1945, updated versions are released annually. This is because of the rate at which the flu virus evolves. Due to the velocity of the virus’ evolution, a prior year’s vaccine might not afford protection against a current strain. As such, companies manufacture new vaccines yearly to keep up with the virus. 

Pfizer encoded strains recommended by the World Health Organization(WHO) for the Northern Hemisphere 2022-23 cell culture in their quadrivalent modRNA vaccine candidate. Quadrivalent vaccines offer protection against four different influenza strains simultaneously. 

Pfizer’s Phase 3 Clinical Trial Begins

The goal of the Phase 3 study is to test the quadrivalent modRNA vaccine’s efficacy, safety, tolerability, and immunogenicity compared to the licensed quadrivalent influenza vaccine (QIV). Twenty-five thousand randomly selected healthy adults in the US are the subject of the study. 

Data from an ongoing Phase 2 trial demonstrating the safety and immunogenicity profile of the vaccine forms the basis of the Phase 3 trial. In addition, the trial is part of Pfizer’s broader influenza vaccine program, focused on leveraging mRNA technology in a vaccine to help protect against the flu.

On the trial, Annaliesa Anderson, Ph.D., Senior Vice President, and Chief Scientific Officer, Vaccine Research and Development at Pfizer, said, “We are excited to start the first Phase 3 efficacy study of an mRNA-based influenza vaccine that could potentially deliver an improved flu vaccine to help address the significant burden of this disease.”

The trial will conclude in June 2023, just in time for that year’s flu season.

Author

Max Heirich