FDA will limit the use of GlaxoSmithKline and Vir's COVID-19 antibody treatment in some geographic areas

When it comes to combating mild to moderate cases of COVID-19, oral antivirals are gaining favor while monoclonal antibody treatments are fading fast—at least for now.

Now, the FDA has put limits on its emergency use authorization of GlaxoSmithKline and Vir Biotechnology’s sotrovimab, saying it shouldn’t be used in geographic areas where the disease was likely caused by a variant that isn’t susceptible to the antibodies.

The FDA did not specify which areas would be affected.

“FDA will monitor conditions to determine whether use in a geographic region is consistent with this scope of authorization, referring to available information, including information on variant susceptibility,” the FDA said Wednesday in a fact sheet for healthcare providers describing when sotrovimab should be used.

RELATED: GlaxoSmithKline and Vir's sotrovimab stands up to omicron despite other COVID antibodies falling short

When the omicron variant first emerged, sotrovimab was one of the few antibody treatments that was shown to be effective against it. With the emergence of the omicron subvariant, BA.2, Vir originally said sotrovimab retained its neutralizing activity. But a recent study suggests the subvariant is resistant to nearly all available monoclonal antibody treatments.

Late last year, with the spread of omicron, GSK and Vir’s drug suddenly became the favored treatment while alternatives from Eli Lilly and Regeneron were relegated to the sidelines. The U.S. already had purchased an undisclosed amount of the doses from GSK and Vir in a $1 billion deal.  

Because COVID-19 is a moving target, this is not the first time the FDA has limited antibodies to certain geographies. Last year, as variants first identified in Brazil and South Africa spread in the U.S., the FDA banned the use of Lilly’s bamlanivimab in some states. Later, the FDA restricted the use of Lilly’s cocktail of bamlanivimab and etesevimab altogether.

In the meantime, Regeneron’s antibody treatment did a booming business as it was shown to retain its effectiveness against the variants. Then, later in the year, when the delta variant emerged, Lilly regained its authorization to supply its antibodies, giving doctors an additional tool to fight the virus with along with Regeneron’s treatment.

After omicron hit the scene, though, the FDA recently pulled its authorizations for the Lilly and Regeneron drugs.

RELATED: Eli Lilly's COVID-19 antibody halted in 6 more states as Regeneron's competing option sails along

Earlier this month, a new Lilly antibody treatment, bebtelovimab, gained emergency use authorization from the FDA. Lilly said the drug was shown to be effective against both omicron and its subvariant. It also has an advantage in its smaller dosage and quicker administration. Lilly has agreed to supply 600,000 doses to the U.S. in a $720 million deal.

Meanwhile, production of Merck’s molnupiravir COVID-19 pill and Pfizer’s more effective oral antiviral Paxlovid is speeding along with supply catching up to demand.