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Do vaccines work against omicron? Lab studies are coming, but won't tell whole story.

Lab findings will be among the first tangible results on the omicron variant, but they'll just be one part of the puzzle.
Ned Landau, virologist at New York University, is studying how antibodies respond to the omicron variant.
Ned Landau, virologist at New York University, is studying how antibodies respond to the omicron variant.NYU Langone Health

In a lab at New York University, Ned Landau is growing an engineered version of the new omicron variant of the coronavirus. 

Landau, a virologist, is going to use this “pseudovirus” — which can’t infect humans — to understand how well antibodies produced by the Covid vaccines can fight off the variant.

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As the omicron variant spreads across the globe, scientists are racing to determine what kind of protection the vaccines offer against the new, highly mutated strain. In academic labs like Landau’s, as well as at the lab benches of pharmaceutical companies including Pfizer and Moderna, researchers are hoping to soon have initial results. 

These lab studies, called neutralization assays, will be among the first data available on how well the vaccines work against omicron, but experts caution that they’ll only be a piece of the puzzle — not one that could alone be used to determine if new, omicron-specific vaccines are warranted

“The laboratory data itself that we get in the next two weeks I don’t think will be sufficient to call for a new vaccine,” Landau said. It’s his expectation that the variant will be somewhat more resistant to vaccine-induced antibodies, as it has a large number of mutations in the part of the virus that the antibodies bind to, called the receptor binding domain.

“While lab data will tell you whether it is capable of escaping the immune response, it won’t really tell you whether we have to do something about it” yet, said Deepta Bhattacharya, a professor of immunology at the University of Arizona.

He also expects the antibodies produced by the vaccines to be less effective in binding to and neutralizing the omicron variant. But that’s not the only factor that needs to be considered; the beta variant, discovered in South Africa earlier this year, also led to a reduction in neutralization, he said. But because it wasn’t as transmissible as the delta variant, it never gained a foothold to spread widely.

The transmissibility of the omicron variant is another part of the story, one also needed to gain a fuller understanding of the variant’s threat. 

Trevor Bedford, a computational biologist at the Fred  Hutchinson Cancer Research Center in Seattle, has been studying the outbreak of the omicron variant in real-time. According to early calculations using data from South Africa, he estimates it could be spreading three to five times faster than delta ever did. Still, these are early estimates, and researchers will have a much better sense after analyzing data from other parts of the world. 

What he is paying most attention to in the coming weeks is the number of people that an infected person spreads the virus to, a number that’s impacted by vaccination rates, previous infections, testing, and mitigation measures like wearing masks. 

During the summer delta surge in the United States, this number was about 1½ , he said. For the current omicron surge in South Africa, it’s roughly 2 ½ , meaning early indications are that this variant may be more transmissible. The number may end up being lower in other parts of the world with higher vaccination rates, however. 

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Experts are also eager to see whether cases rise as the omicron variant spreads, and whether it can outcompete delta to become the predominant variant around the globe. 

Bedford also estimated that omicron will lead to a significant drop in antibody effectiveness, one that could be as high as a  twentyfold reduction in neutralizing ability compared to the original strain of the virus.  This compares to a fourfold reduction for delta and an eightfold reduction for beta. However, these estimates are for two doses of an mRNA vaccine — boosters will improve the antibody response against all variants, he said. 

And while protection against mild or moderate illnesses may wane because of omicron, protection against severe disease is likely to remain intact, experts predict.

“There’s every reason to think that boosting now will be even more important than we realized,” Landau said. “Boosting broadens the antibody response to be able to bind to more different variants of the virus, so it has the effect of increasing the protection against even something like omicron.”

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