Racing Moderna, Pfizer starts phase 3 trial of mRNA flu vaccine

Pfizer has begun a phase 3 clinical trial of its mRNA-based influenza vaccine, keeping it tucked in behind Moderna in the race to upend the seasonal flu market using the technology that defined the response to COVID-19.

Moderna dosed the first participants in a phase 3 clinical trial of its flu vaccine candidate, mRNA-1010, in June, activating sites in the Southern Hemisphere to get data to support a potential accelerated approval while preparing to run a larger confirmatory study in the Northern Hemisphere in the 2022-23 flu season. Pfizer, taking a different approach, has made a 25,000-subject U.S. phase 3 the focus of its program. 

The investigators have now dosed the first participants with Pfizer’s quadrivalent modified RNA influenza vaccine. Through the trial, which is enrolling people aged 18 years and older, the Big Pharma is aiming to show the efficacy, safety, tolerability and immunogenicity of the vaccine.

If the study is successful, Pfizer will have a shot at disrupting a market that has long accepted highly variable—and sometimes low—efficacy as an unavoidable consequence of the challenge of protecting against an ever-changing mix of pathogens. 

“For years, there has been a need to better address the burden of influenza, despite the use of existing seasonal flu vaccines,” Annaliesa Anderson, Ph.D., chief scientific officer of vaccine R&D at Pfizer, said in a release.

“Our experience with RNA viruses and mRNA technology has given us an even deeper understanding of the opportunity to potentially provide more efficacious vaccines that could further reduce the yearly rates of the severe outcomes of viral disease like flu, including hospitalization and death.”

Pfizer secured the chance to apply mRNA to flu vaccines in 2018 when it offered BioNTech $120 million in upfront and near-term payments, and interest in the program has escalated since COVID-19 validated the power of the modality to protect against viral pathogens.  

The opportunity has attracted a small band of other players, with Sanofi having generated early-phase data on a monovalent vaccine last year and planning to move a quadrivalent candidate into the clinic by the end of 2022. Moderna’s quadrivalent candidate is leading the way, though, with its Southern Hemisphere trial now fully enrolled and on course to deliver data early next year.