New data on BA.2.86 suggest the fall booster may work well

Since BA.2.86 emerged a couple of weeks ago, scientists around the world have been racing to evaluate this variant. Several teams posted data in the last week, and the news is promising: while BA.2.86 does have an advantage over past variants, the lab findings suggest that vaccines (including the upcoming boosters) and past infections provide protection against it.

The new studies come from research groups in the U.S., China, Japan, Switzerland, and South Africa. These scientists studied BA.2.86 by growing the variant in petri dishes and evaluating it against antibodies from blood samples. Overall, they found that BA.2.86 can infect people who were recently infected with XBB.1.5 and its relatives, but this variant isn’t as successful at getting into human cells as XBB.1.5.

Another notable study came from researchers at Moderna, who evaluated how the company’s upcoming booster shot performs against BA.2.86. This team found that the booster—which is designed from XBB.1.5—helps the immune system prepare for XBB variants as well as BA.2.86. While lab studies like this one don’t translate perfectly to real-world effectiveness, the data do suggest that Moderna’s booster should protect well against BA.2.86 infection for a few weeks after vaccination, and against severe disease for longer.

You might have seen the figure below shared around on social media in the last few days. This chart, from the Moderna team, shows how the new booster improves immunity toward several variants. For example, patients who received the booster had 8.7 times more neutralizing antibodies against BA.2.86 and 10 times more neutralizing antibodies against XBB.1.5 than those who had not received it.

This figure, from a preprint by Moderna scientists, shows how the company’s upcoming fall booster performs against different variants.

Pfizer has also tested their new booster against BA.2.86 and found similar results, according to a report from Reuters. This company’s results have yet to be shared in a scientific paper, though.

The studies I’ve discussed here are all preprints, meaning the results have yet to be peer-reviewed (outside of the informal review process that happens on social media for this type of urgent research). It’s also worth noting that lab studies look at immune system signals, rather than actually tracking who’s getting this new variant and their disease outcomes.

Even if BA.2.86 is not “the next Omicron,” as some scientists suggested based on its mutations, it could still contribute to a new uptick in cases this fall. And all cases carry the risk of severe illness, Long COVID, and other poor outcomes. The new boosters are likely to help reduce risk (which is good news), but other measures are still needed.

References about the new studies:

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