Scientists are keeping a close watch on BA.2, a subvariant of the omicron variant, as it spreads through the United States. The concern is that while Covid-19 vaccines appear to effectively protect against BA.2, it has the ability to overpower some antibody treatments.
Covid-19 antibody treatments, from drugmakers Regeneron and Eli Lilly, have already been found to not work against the original omicron strain that accounts for nearly all new coronavirus infections in the U.S. The hope has been that an antibody treatment from GlaxoSmithKline and a newly authorized antibody drug from Eli Lilly would help treat mild-to-moderate cases of omicron and keep people out of the hospital.
A study, which was published to a preprint sever Wednesday and has not yetbeen peer-reviewed, now suggests that the BA.2 subvariant is resistant to sotrovimab, the monoclonal antibody drug from GSK and Vir Biotechnology that’s the most recommended treatment in the U.S. against omicron.
The researchers, testing the treatment on an engineered version of the virus made in a lab, found that BA.2 is not neutralized by the therapeutic monoclonal antibodies, including sotrovimab.
If the researchers’ findings are confirmed through additional studies and real-world data, the omicron subvariant may represent a looming threat to Americans, especially those at high risk who may not mount an adequate immune response from vaccination, health experts say.
“That’s something we’re watching very, very closely,” Dr. Rajesh Gandhi, an infectious-disease specialist at Massachusetts General Hospital, said at a virtual briefing Friday with the Infectious Diseases Society of America.
“I know more information will come,” he said, “and I know the CDC is monitoring very, very carefully the spread of BA.2 to see if it’s going to stay stable at a very low level or whether it’s going to increase as a proportion of omicron cases.”
So far, the BA.2 subvariant, thought by scientists to be the most transmissible version of the coronavirus to date, has not been spreading widely in the U.S. It accounted for roughly 4 percent of all new Covid cases for the week ending Feb. 12, according to data from the Centers for Disease Control and Prevention.
While BA.2 has already largely replaced the original omicron strain in parts of Asia, South Africa and Denmark, “it has mysteriously failed to do so in the U.S, said Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health.
In Denmark, with the lifting of many Covid restrictions, cases are currently skyrocketing.
Gandhi noted that the Eli Lilly drug, called bebtelovimab, has been shown in lab studies to work against all other known variants of interest and concern, including BA.2.
The Biden administration has purchased 600,000 doses of the Lilly drug. About 300,000 treatment courses of the new antibody drug are expected to ship by the end of the month, and another 300,000 in March.
Universal Covid treatments needed
Still, Gandhi said emerging data on BA.2 suggess scientists may need to develop new treatments that target parts of the virus that are unlikely to change as it mutates.
“Just as people are talking about a universal coronavirus vaccine, a vaccine that targets a broad variety of coronaviruses, I think similarly we need universal coronavirus treatments,” Gandhi said.
Scientists should also focus on developing different kinds of treatments or even drugs used in combination, Dr. Adarsh Bhimraj, an infectious diseases specialist at the Cleveland Clinic, said at the same briefing.
He said that if scientists focus only on monoclonal antibody treatments then “we will continue to exhaust our options” because new variants will continue to emerge.
Antiviral drugs, from Pfizer and Merck, for example, work by introducing errors or blocking enzymes that the virus needs to replicate in the body. They are different from monoclonal antibody treatments, which are designed to mimic an immune response.
“I’m very optimistic, but I think we can still do much better not just in developing newer agents, but in looking at how we can use these agents in combination to treat emerging resistance,” he said.
Treatments and therapies also need to be developed for people who aren’t at high risk of severe disease, said Dr. David Boulware, an infectious disease physician at the University of Minnesota Medical School.
Even though healthy vaccinated people who get breakthrough infections with omicron are unlikely to end up in the hospital, “they can still feel terrible and end up being out of work for a week or two,” he said.
Gandhi said he would encourage larger studies that look at repurposed drugs.
“We’ve made progress in the last year because clinicians and their patients were willing to do these larger randomized studies to get a definitive answer,”