Early results look good for a ‘universal’ flu vaccine that could stop the next pandemic

Early results look good for a ‘universal’ flu vaccine that could stop the next pandemic

In these flu names, the “H” stands for hemagglutinin, which is a protein that the virus uses to stick to the outside of the cell. “N” is something opposite. It is a neuraminidase protein for which the virus uses to escape from the cell after reproduction. If you think of human cells as having lots of entrances and exits, each with a different lock, H and N are the keys the virus carries to get in and out.

If two viruses are encoded as H5N1 and H5N3, they both carry the same (or similar) version of hemagglutinin, but carry completely different versions of neuraminidase. However, if someone was recently infected with the first virus, they would have fairly good protection against the second. However, if something like H3N2 emerges, none of the defenses the body has in place against H5N1 would hold up.

Each year, researchers look at the flu cases they see, paying attention to those that haven’t been around for a while, and try to produce a vaccine that hits the most likely species. They are particularly concerned when they see a virus in animals that carries a pair of proteins that has not appeared in humans for decades.

That’s what makes this new vaccine strategy so exciting.

Current flu vaccines, composed of four influenza virus antigens, offer little protection beyond the virus strains that the vaccines target. Universal flu vaccines that can protect against all 20 lineages could help prevent the next pandemic. Designing and manufacturing a vaccine that can provide such broad protection has been challenging, but demonstrating the feasibility of a COVID-19 mRNA-lipid nanoparticle vaccine offers a possible strategy.

If vaccine design seems to include almost all the buzzwords for new vaccine technologies, you’re right. BioNTech and Moderna’s COVID-19 mRNA vaccines are the first to be approved for use in humans. But now that the door is open, this technology has enormous potential, including the ultimate flu vaccine.

The vaccine produced by the Penn team targets all 18 known versions hemagglutinin. So, even if something like the current bird flu were to spread to humans tomorrow, we would already have a vaccine that is essentially effective.

This would not mean an end to annual flu shots, and those shots would still focus on the types most likely to be seen in season. However, they can also significantly reduce the chance of getting seriously ill from any flu.

Several steps remain to show that this vaccine is safe and effective in humans. Among other things, there is concern that obtaining enough vaccine to generate responses to all 18 versions of “H” could be shown to require too high a dose, leading to unpleasant reactions. (This is precisely why it is difficult to make a universal vaccine against COVID-19 that applies to all known variants.)

But since the technologies involved in this vaccine have already been tested against COVID-19, expect this vaccine to advance without concerns about the use of mRNA or lipid capsules. It will not be part of any vaccine you use this year. But next year? Could be.



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