mRNA Flu Vaccines Show Promising Results in Clinical Trials

Innovations in flu vaccination are underway as mRNA flu vaccines progress through clinical trials. Data from a phase 3 trial indicate that Pfizer’s mRNA flu vaccine outperformed traditional vaccines during the 2022–2023 flu season. The findings were published in the November 20 edition of the New England Journal of Medicine.

Researchers compared the efficacy of the mRNA vaccine to that of a conventional flu vaccine. The trial demonstrated that the mRNA vaccine reduced the incidence of flu among participants by approximately 35 percent when assessed at least 14 days post-vaccination. This significant relative efficacy suggests that the mRNA vaccine was more effective in preventing illness than its traditional counterpart during that flu season.

The study enrolled over 18,000 healthy adults aged 18 to 64 from the United States, South Africa, and the Philippines. The mRNA vaccine specifically targeted hemagglutinin, a protein that facilitates the influenza virus’s entry into human cells. It included variations of this protein from four different flu strains, following the recommendations established by a World Health Organization (WHO) committee, which determines the strains to be included in vaccines each flu season.

In a related development, Moderna also announced results from its phase 3 trial for an mRNA flu vaccine aimed at adults aged 50 and older. This vaccine achieved a relative efficacy of about 27 percent compared to traditional flu vaccines and involved nearly 41,000 participants from 11 countries. Individuals aged 65 and above are particularly vulnerable to severe flu complications, making effective vaccination critical.

The mRNA technology presents a promising solution for improving flu vaccine efficacy. One notable advantage is its quicker production turnaround, allowing for more flexibility in responding to emerging flu strains. Currently, WHO’s recommendations for vaccine composition need to be made early enough to accommodate the up to six months required for producing traditional vaccines. If a new flu strain emerges late in the season, it may not be effectively covered by that year’s vaccine.

As the Northern Hemisphere approaches its flu season, early data suggests that a variant, which gained prevalence during the Southern Hemisphere’s flu season, is now dominating flu samples in England and Japan. Unfortunately, this variant appeared too late for inclusion in the Northern Hemisphere’s vaccine formulation.

As research continues, the introduction of mRNA flu vaccines could provide a vital new tool in the fight against influenza, potentially offering better protection and adaptability in an ever-changing viral landscape.