The medical association, which represents more than 12,000 specialists, said its guidelines panel is evaluating available trial data and will issue its recommendations soon.

The Food and Drug Administration on Monday authorized Lilly's bamlanivimab for people over age 65 recently diagnosed with mild-to-moderate COVID-19, and for patients age 12 and older who have an underlying risk factor for serious illness, such as obesity or diabetes. The agency said the drug should not be used in hospitalized patients.

"It is important for clinicians and members of the public to be aware that the available data are limited, and that more information is needed to determine the effect of this therapy on clinically meaningful outcomes," the IDSA said in a statement.

The association has updated its COVID-19 treatment guidelines several times over the course of the pandemic, adding drugs like Gilead Sciences Inc's antiviral remdesivir and generic steroids as trial data have emerged.

It does not always follow the lead of the FDA, which in August authorized emergency use of plasma derived from COVID-19 survivors for treating patients hospitalized with the illness. The IDSA still advises that convalescent plasma only be used in the context of a clinical trial.

"For new therapeutics to be used widely and routinely outside of clinical trials, we urge that there be sufficient safety and efficacy data to be confident regarding their use," the group said.

The IDSA said it is also concerned about the limited supply of the Lilly antibody treatment.

The Department of Health and Human Services said it has purchased 300,000 doses of the drug and will begin distributing them free-of-charge this week to state health departments.

(Reporting by Deena Beasley; Editing by Bill Berkrot)

By Deena Beasley