A new flu vaccine might not seem like a big deal, but this isn’t the kind of vaccine you can currently get at the local pharmacy. In a study published this week in Science, researchers from the University of Pennsylvania reported the first results from animal trials of a new messenger RNA-based vaccine against the flu.

This is not a vaccine against a specific strain of flu, like those which are mixed together to generate the cocktail seen in annual flu shots.

The reason that flu is so difficult to stop, and that it returns year after year in spite of readily available vaccines, is that flu viruses have a revolving set of surface proteins that can be swapped out without affecting the virus’ effectiveness, while allowing the virus to bypass existing immunity.

So people can catch Influenza Type A H3N2 in one season, the follow it up with H5N1 the next year.

Current influenza vaccines, composed of four influenza viral antigens, provide little protection beyond the viral strains targeted by the vaccines.

Universal influenza vaccines that can protect against all 20 lineages could help to prevent the next pandemic.

Designing and manufacturing a vaccine that can provide such broad protection has been challenging, but the demonstration of the feasibility of mRNA–lipid nanoparticle COVID-19 vaccines offers a possible strategy.

The vaccine produced by by the Penn team targets all 18 known versions of hemagglutinin.  So even if something like the current flu being passed around among bird species makes the leap to humans tomorrow, we would already have a vaccine that was substantially effective. .