The FDA halted the use of two monoclonal antibody treatments for COVID-19 because they are not effective against the omicron variant of SARS-CoV-2, which now accounts for almost all U.S. cases.

The FDA revised the emergency use authorizations for the two treatments bamlanivimab and etesevimab administered together, and the cocktail of casirivimab and imdevimab. Their use will now be limited to infections that are likely to have been caused by a variant that is susceptible to the treatments.

“Because data show these treatments are highly unlikely to be active against the omicron variant, which is circulating at a very high frequency throughout the United States, these treatments are not authorized for use in any U.S. states, territories, and jurisdictions at this time,” Patrizia Cavazzoni, MD, director of the FDA’s Center for Drug Evaluation and Research, said in a press release.

Cavazzoni said this will avoid exposing patients to side effects from treatments “that are not expected to provide benefit to patients who have been infected with or exposed to the omicron variant.”

She said the treatments may be reauthorized in regions where patients are likely to be infected or exposed to a susceptible variant, or if they are proven affective against future variants.

The FDA noted that there are several other therapies that are expected to work against omicron, including Paxlovid, sotrovimab, remdesivir and molnupiravir.

“Health care providers should consult the NIH panel’s COVID-19 treatment guidelines and assess whether these treatments are right for their patients,” Cavazzoni said.