mRNA Flu Vaccines Show Promise in Clinical Trials Across Countries

The development of mRNA flu vaccines is advancing, with promising results emerging from recent clinical trials. Pfizer’s mRNA flu vaccine demonstrated a significant advantage over traditional vaccines, according to researchers in a study published in the November 20, 2023 edition of the New England Journal of Medicine. The phase 3 trial, conducted during the 2022–2023 flu season, revealed that the mRNA vaccine reduced the incidence of flu by approximately 35 percent compared to conventional vaccines.

More than 18,000 healthy adults aged 18 to 64 from the United States, South Africa, and the Philippines participated in the trial. The mRNA vaccine specifically targeted hemagglutinin, a critical protein that allows the influenza virus to penetrate cells, incorporating variations from four different flu strains. Each flu season, a committee from the World Health Organization (WHO) recommends which strains to include in vaccines based on current circulation patterns.

In June 2023, Moderna also reported results from its phase 3 trial of an mRNA flu vaccine aimed at adults aged 50 and older. This vaccine showed a relative efficacy of approximately 27 percent against traditional flu vaccines, involving nearly 41,000 participants across 11 countries. The elderly are particularly vulnerable to severe flu complications, making advancements in vaccination technology crucial.

The mRNA platform presents a faster production turnaround, potentially enabling manufacturers to respond more effectively to emerging flu strains. Currently, the WHO’s vaccine composition recommendations must be made early enough to allow for the lengthy production process of up to six months for traditional vaccines. This timeline poses challenges when a late-breaking flu strain begins to dominate, as seen with a variant that emerged during the Southern Hemisphere’s flu season, which is now prevalent in samples from England and Japan. This variant was not included in the Northern Hemisphere’s vaccine as it arose too late for consideration.

The emergence of effective mRNA flu vaccines could significantly enhance public health strategies against influenza. As these technologies continue to develop, they may offer a vital tool in combating seasonal flu outbreaks while addressing the limitations of traditional vaccine production methods.