Landmark 20-strain mRNA flu vaccine looks to prevent future pandemics

An incredible new study published in the journal Science demonstrates the potential for a single mRNA vaccine to provide protection from all 20 known influenza A and B virus subtypes. It's hoped the vaccine, so far seen to be effective in preclinical animal models, would prevent future flu pandemics by promoting immunity against influenza strains yet to cross over from animals into humans.

Older vaccine technology is unable to pack 10 or 20 different antigens into a single shot, but mRNA technology, in theory at least, doesn't face these limitations. So far, with the introduction of the latest bivalent Omicron mRNA vaccine booster, researchers have incorporated two particular antigens into the one shot.

But what if a single vaccine could help teach the immune system how to recognize dozens of different iterations of the same virus? It is this very idea that researchers at the Perelman School of Medicine at the University of Pennsylvania explored in their landmark study.

The key antigenic target in influenza vaccines is a molecule called the hemagglutinin protein. It sits on the surface of the virus and is crucial to its infectivity. Each strain of influenza carries its own uniquely shaped hemagglutinin protein. The experimental mRNA vaccine tested in this new research covers 20 different influenza hemagglutinins: all 18 known subtypes of influenza A and two subtypes of influenza B.

The newly published study reported testing the multivalent vaccine in mice and ferrets. As explained by Scott Hensley, senior author on the new study, the big takeaway from these experiments is the animals seemed to develop distinct antibodies against all 20 influenza strains. This shows a single mRNA vaccine can effectively deliver broad protection against a large number of different antigens.

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