Closeup of gloved hands preparing an infusion bottle

Clinicians in the United States relied strongly on the use of two monoclonal antibody (mAbs) treatments for COVID-19, even after they were deauthorized by the Food and Drug Administration, according to a new study.

Investigators at Beth Israel Deaconess Medical Center in Boston found that hospitals and health systems administered more than 158,000 doses of Eli Lilly’s bamlanivimab and etesevimab and Regeneron’s REGEN-COV (casirivimab and imdevimab) in early 2022, although patients “had a minimal likelihood of benefit,” they reported.

The two mAb options were authorized to much fanfare in 2021 and 2020, respectively. Clinicians at the time had limited options to offer patients in the recommended treatment group, which included high-risk ambulatory patients with mild to moderate COVID-19. But the drugs were later shown to be ineffective against the omicron variant, which roared onto the scene in late 2021 and by late January accounted for 99% of COVID-19 cases nationwide.

Currently, bebtelovimab is the only mAb that federal health officials recommend for use in treating adults with mild to moderate COVID-19 who are at high risk of progressing to severe disease.

Confused clinicians?

The way in which the other mAbs were deauthorized may have confused some clinicians, said study author Jennifer Stevens, MD, and colleagues. The FDA made it clear that the mAbs were no longer recommended for use, but it did not fully revoke their emergency use authorizations in case future COVID-19 variants turned out to be susceptible. 

The continued use of the mAbs may also reflect conflicting state government guidance, or lack of hospital awareness about deauthorization, the researchers added. 

In any case, with Medicare payments for mAb administration ranging from $450 to $750 per dose, spending on these treatments likely cost patients more than $71 million, the authors reported. The investigators were unable to examine facility-level use, as public data is aggregated to the state level. 

Full findings were published in JAMA Network Open.