FDA limits Covid therapy as ineffective against Omicron BA.2 variant

U.S. health officials on Friday stopped the further deployment of the Covid-19 treatment sotrovimab to places where the BA.2 coronavirus variant is now causing the majority of infections, given laboratory studies showing the treatment likely doesn’t work against the variant.

States in New England, as well as New York, New Jersey, Puerto Rico, and the Virgin Islands, will no longer receive shipments of the monoclonal antibody therapy made by Vir Biotechnology and GSK, officials said.

This is not the first time that the evolution of the SARS-CoV-2 virus has undercut the power of certain antibody therapies, which have generally been designed to target the virus’ spike protein. When the Omicron family of viruses took off late last year, the government halted shipments of antibody therapies made by Lilly and Regeneron when it became clear that they would no longer work against the strains that were circulating.

advertisement

Notably, sotrovimab maintained its effectiveness against the first form of Omicron that became dominant, the BA.1 lineage. But several lab studies in recent weeks have indicated the therapy loses much of its ability to neutralize the BA.2 lineage.

It can be difficult to extrapolate what those lab data mean for clinical effectiveness, but “it just seems likely that when the antibody is so weak in the lab, that it’s not going to work well in patients,” said Nathaniel Landau, a virologist at NYU’s Grossman School of Medicine and the senior author of one of the studies.

advertisement

Losing yet another antibody treatment highlights how the virus has been able to race ahead of some therapeutic strategies, experts said. While antiviral treatments have maintained their potency against the different variants, the monoclonals are more vulnerable to a fast-changing virus. “It’s expensive and a lot of work to develop these monoclonal antibodies, and then so rapidly the virus can just escape,” Landau said. “That’s what we’ve learned from Covid.”

The United States is not in the same place as when the Omicron family first emerged and threatened our arsenal of treatments. For one, far fewer cases are being reported each day, so there is less demand for treatments. Moreover, supplies of other treatments — including the oral antivirals Paxlovid and molnupiravir — have increased in recent months.

The Food and Drug Administration last month also authorized another monoclonal antibody therapy, Lilly’s bebtelovimab, that lab data indicate can work against BA.2.

The treatments are generally reserved for Covid patients who are at high risk of getting so sick they could be hospitalized.

Already, some doctors had started to adapt their treatment plans as BA.2’s prevalence grew.

Rajesh Gandhi, an infectious diseases physician at Massachusetts General Hospital, said his first choice for patients was typically Paxlovid. People on certain medications, however, can’t take the drug, so his No. 2 choice had generally been sotrovimab, he said.

But as BA.2 took off in Massachusetts, he started looking more to bebtelovimab and the intravenous antiviral remdesivir over sotrovimab.

“It’s kind of reshuffling the order of things,” Gandhi said.

The most recent federal data available indicate that BA.2 has overtaken its sister Omicron lineages in the northeastern United States and is responsible for about 1 in 3 infections nationally. It is expected to become the dominant variant in the country shortly. It’s thought to be some 30% to 50% more transmissible than the BA.1 lineages, though it appears to cause the same average disease severity and vaccines work just as well against it as other forms of the Omicron variant.

The ascendance of BA.2 — and BA.2-driven surges in Europe — has alarmed some experts, who have warned the United States could be vulnerable to another surge, particularly as mitigation efforts eased and people took fewer precautions.

But health officials have been heartened that even as BA.2 has become dominant in some regions, cases haven’t taken off explosively. Perhaps some regions — or even the whole country — could see a bump in cases, but not a huge spike.

At a briefing this week, Rochelle Walensky, the director of the Centers for Disease Control and Prevention, said there have been increases in infections in New York state and New England, and some uptick in hospitalizations, but that there was no strain on hospitalizations.

“I want to emphasize that these upticks reflected minor increases from very low levels to still very low levels, but sustained trends over time can give us an early indication of Covid-19 infections in communities,” Walensky said.

What’s happening with BA.2 in the United States reflects how the same version of the virus can behave differently based on the local landscape. In South Africa, BA.2 took over from BA.1 without causing a resurgence of cases. In Europe, BA.2 piggybacked on BA.1 in some countries like Denmark and caused an infection spike on top of a spike, while in others the BA.1 wave had subsided before BA.2 ignited another one.

If the United States avoids a BA.2 wave, it could be for several reasons. In the spring, more activities in the northern part of the country move outside, and we haven’t reached the point in the southern part of the country where it’s so hot that people migrate inside. The country also experienced a massive BA.1 wave, and it seems that immunity from that variant — particularly if it was layered on top of protection from vaccines or earlier infections — can generally withstand BA.2 for at least some time.