Progress is being made in the development of mRNA flu vaccines, with clinical trials showing promising results. A recent study published in the New England Journal of Medicine on November 20, 2023, detailed the findings of a phase 3 trial conducted by Pfizer. The trial revealed that Pfizer’s mRNA flu vaccine outperformed a traditional flu vaccine during the 2022–2023 flu season.
The trial involved more than 18,000 healthy adults aged 18 to 64, across the United States, South Africa, and the Philippines. Researchers evaluated the effectiveness of the mRNA vaccine by comparing the incidence of flu among participants who received the vaccine versus those who received the traditional vaccine. Results indicated that the mRNA vaccine reduced the likelihood of contracting the flu by approximately 35 percent compared to its conventional counterpart.
Significant Findings from Phase 3 Trials
The mRNA vaccine developed by Pfizer specifically targeted hemagglutinin, a crucial protein that enables the influenza virus to infiltrate human cells. The vaccine contained formulations for four different flu strains, which were selected based on recommendations by a committee from the World Health Organization (WHO).
In a related development, Moderna also announced phase 3 trial results for its own mRNA flu vaccine designed for adults aged 50 and older. This vaccine demonstrated a relative efficacy of about 27 percent when compared with traditional flu vaccines, involving nearly 41,000 participants across 11 countries.
The elderly, particularly those aged 65 and older, are at a heightened risk for severe complications associated with influenza. The introduction of an mRNA flu vaccine could present a valuable new strategy for combating the influenza virus. A significant advantage of the mRNA platform is its quicker production timeline, which allows for timely adjustments to vaccine formulations based on emerging flu strains.
The Challenge of Vaccine Match
Currently, the WHO must finalize its vaccine composition recommendations well in advance of flu seasons to accommodate the lengthy production process for traditional vaccines, which can take up to six months. This advance planning can lead to mismatches if new flu strains emerge after recommendations are made.
As the Northern Hemisphere approaches its flu season, early data indicates that a variant which gained traction during the Southern Hemisphere’s season is now prevalent in flu samples from England and Japan. Unfortunately, this variant arose too late to be considered for inclusion in the upcoming Northern Hemisphere vaccine.
As researchers continue to investigate the efficacy of mRNA flu vaccines, their potential to enhance seasonal flu prevention strategies remains a topic of great interest within the medical community. The continued development and success of these vaccines could ultimately lead to more effective flu prevention, particularly for those most vulnerable to severe illness.
