Monoclonal antibody combo keeps high-risk COVID-19 patients out of hospital

Treatment with two monoclonal antibodies lowers the odds of hospitalization for high-risk COVID-19 patients with mild to moderate illness, according to a new study.

"Our conclusion overall at this point is that monoclonal antibodies are an important option in treatment to reduce the impact of COVID-19 in high-risk patients," said senior author Dr. Raymund Razonable, an infectious diseases specialist at the Mayo Clinic in Rochester, Minn.

The combination of casirivimab and imdevimab has emergency use authorization from the U.S. Food and Drug Administration.

The study included 696 COVID-19 patients treated with the combo at the Mayo Clinic between December 2020 and early April 2021, and an equal number of patients who didn't receive it.

The patients were evaluated 14, 21 and 28 days after treatment. At each checkpoint, fewer patients who had been treated with the combo were hospitalized.

At Day 14, 1.3% of treated patients and 3.3% of untreated patients were in the hospital. A week later, 1.3% of treated patients were still in the hospital, compared to 4.2% of others. At Day 28, the percentages were 1.6% of treated patients and 4.8% of others.

Overall, patients who received the combo therapy had a 60% to 70% lower risk of hospitalization than untreated patients, the findings showed.

Of the treated patients who were hospitalized, rates of admission to the intensive care unit and death were low, according to the report published Aug. 30 in the journal EClinicalMedicine.

"Once again, this real-world study suggests that when patients who are at high risk ... contract a mild or moderate case of COVID-19, this combination of monoclonal injections gives them a chance of a nonhospitalized recovery," Razonable said in a Mayo Clinic news release. "In other words, they recover safely at home."

In a previous study, Mayo Clinic researchers found that treatment with the monoclonal antibody bamlanivimab reduced hospitalizations among high-risk patients by 40% to 60%, and also significantly lowered their ICU admission and death rates.

In April, however, the FDA revoked its emergency use authorization for bamlanivimab alone and now endorses the use of combination monoclonal antibodies, the study authors noted.

More information

The U.S. Department of Health and Human Services has more about monoclonal antibodies for COVID-19.