Eli Lilly and Co’s bamlanivimab monoclonal antibody therapy reduces the risk of COVID-19 in residents and staff of skilled nursing facilities and assisted living communities, according to a new investigation.

Since the study was conducted, the Food and Drug Administration has revoked emergency use authorization for the drug. New coronavirus gene variants spreading in the United States had begun to interfere with its efficacy. But it still can be used in combination with etesevimab in most states.

A total of 1,175 study participants from 74 nursing homes were randomly assigned to receive a 4,200 mg single intravenous infusion of the drug or a placebo. Bamlanivimab significantly reduced the rate of COVID-19 in participants at high risk of severe illness when compared with placebo. 

It also appeared to be protective in those who contracted the disease, reported first author Myron S. Cohen, M.D., from the University of North Carolina, Chapel Hill. All participants who received bamlanivimab and acquired SARS-CoV-2 had lower baseline viral loads and cleared the virus more quickly than the placebo group, Cohen and colleagues reported.

The results may help validate the use of monoclonal antibodies as “protective passive immunotherapy against COVID-19, with potential clinical relevance for antibody therapies in continued distribution,” they said.

Additional research is needed to gauge how well the drug works in combination with etesevimab against current patterns of viral strains, they concluded.