Federal regulators said they are suspending use of a monoclonal antibody drug known as sotrovimab to treat high-risk Covid-19 patients in the United States because it was unlikely to be effective against the Omicron subvariant which is known as BA.2.
BA.2 is highly transmissible and is now dominant in the United States, four months after it was first discovered in the country. The Centers for Disease Control and Prevention estimated Tuesday that BA.2 was responsible for about 72 percent of new U.S. coronavirus cases in the week ending April 2.
In late March, federal health officials stopped shipping sotrovimab to eight states in the northeast and two territories — Puerto Rico and the U.S. Virgin Islands — where BA.2 had become dominant earlier than the rest of the country.
Doctors treating patients at risk can still use another monoclonal antibody, bebtelovimab, which is manufactured by Eli Lilly. There are also three antiviral treatments that have been shown to be potent against BA.2 in lab tests.
Sotrovimab was widely used in the winter during the wave of cases because it was the only authorized antibody treatment that worked against BA.1, the Omicron subvariant that was dominant at the time.
In January, federal officials restricted the use of two other antibody treatments, from Eli Lilly and Regeneron, which were widely used during the Delta wave last year because they were not potent against BA.1. They are also not expected to work against BA.2.
Sotrovimab’s manufacturers GlaxoSmithKline and Vir Biotechnology said in March that they had determined in lab tests that the drug’s allowable dosage was not sufficiently potent against BA.2, consistent with previous findings from independent researchers. The companies said they were preparing to submit data to regulatory authorities to seek approval for a higher dose that they hope will work against BA.2.
Rebecca Robbins reporting contributed.