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Early tests suggest Vir, GSK antibody could hold up versus omicron

Omicron’s detection last week triggered travel restrictions and renewed public health measures around the world as scientists and government officials warned the variant may more readily spread and cause disease.

But many of the most important questions, such as whether infection from the variant causes more severe symptoms or whether it can sidestep vaccine protection, remain unanswered. Data should be available within the next week or two, as researchers study the variant in greater detail and more cases accumulate.

For vaccine and drug developers, omicron’s threat will initially be measured by lab tests that analyze whether their treatments can still neutralize the variant. Scientists commonly use genetic data to engineer pseudo-viruses that replicate the real thing, rather than use live virus samples. Those pseudo-viruses are then mixed with blood from vaccinated individuals or, in the case of antibody drugs, the medicines themselves.

The data released by Vir and GSK are an early attempt at this, using already available pseudoviruses that contain some of the same key mutations as found in omicron. For all individual mutations the companies pitted their drug against, they found it retained neutralizing activity. Psuedo-type viruses containing some of omicron’s more concerning mutations, however, weren’t available.

The effect of omicron’s mutations in sum may also be different than each of those mutations individually, meaning Vir and GSK’s data can only be counted on so much to predict whether their drug will be equally effective against omicron as the original coronavirus strain. The drug retained potency against prior variants, including delta.

“We have every expectation that this positive trend will continue and are working rapidly to confirm its activity against the full combination sequence of omicron,” said Vir CEO George Scangos in a statement.

Vir and GSK’s drug, called sotrovimab, is available in the U.S. under an emergency authorization granted by the Food and Drug Administration in May. The companies designed it to bind to a region of the coronavirus’ spike protein that they claim is “conserved” even as the virus mutates.

While Vir and GSK are confident their antibody will work versus omicron, other antibody drug developers aren’t as certain. Regeneron, for example, warned this week that its cocktail of two antibodies may not be effective against the variant, although tests are ongoing.

Vaccine makers, too, are concerned that omicron may escape the immune protection their shots generate and are already readying omicron-specific versions in preparation.