It is the first Phase 3 study to evaluate the efficacy, safety, tolerability and immunogenicity of an mRNA-based influenza vaccine, and is designed to enrol 25,000 individuals in the US, aged 18 years and above


Pfizer initiates Phase 3 influenza vaccine trial. (Credit: Willfried Wende from Pixabay)

US-based pharmaceutical and biotechnology firm Pfizer has commenced the Phase 3 clinical trial of its quadrivalent modified RNA (modRNA) influenza vaccine candidate.

The company dosed the first participants in the study, which will evaluate the efficacy, safety, tolerability and immunogenicity of the vaccine in around 25,000 adults in the US.

The Phase 3 study builds on data from the ongoing Phase 2 study, which showed a safety and immunogenicity profile of program advancement.

It is part of Pfizer’s larger influenza vaccine programme, which targets developing an influenza vaccine leveraging mRNA technology.

Pfizer senior vice president and vaccine research and development chief scientific officer Annaliesa Anderson said: “For years, there has been a need to better address the burden of influenza, despite the use of existing seasonal flu vaccines.

“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.

“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.”

According to the company, mRNA-based vaccines require only the genetic sequences of the viruses and enable rapid manufacturing, improved strain match, and efficacy.

The quadrivalent modRNA vaccine candidate will encode the virus strains recommended by the World Health Organization (WHO) for use in influenza vaccines.

Pfizer developed the vaccine based on the same technology used in its widely-used Covid-19 vaccine, in partnership with German biotech company BioNTech.

In 2018, the US drugmaker entered into an exclusive collaboration and license agreement with BioNTech to develop and commercialise mRNA‐based influenza vaccines.

Once the potential quadrivalent influenza vaccine is approved and commercialised, it would pay BioNTech a royalty on the product sales, said Pfizer.

Furthermore, the company is exploring additional novel mRNA technology beyond the modRNA vaccine candidate, such as self-amplifying RNA (saRNA).