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Lab-made antibodies may help prevent COVID hospitalizations in high-risk patients, Mayo study finds

The findings only apply to "high-risk" patients with a mild or moderate case of COVID.

An injection of laboratory-created antibodies may help high-risk COVID-19 patients avoid hospitalization, according to a recently published Mayo Clinic study.

The world-renowned clinic detailed the findings of its observational study of monoclonal antibody treatments Monday. The study included nearly 1,400 "high-risk" patients that were infected with a mild or moderate case of COVID-19. 

But the Mayo told the Star Tribune it is not a substitute for a COVID-19 vaccine, which provides protection for a much longer period of time, and also significantly reduces the chances of contracting COVID-19 in the first place.

In the Mayo study, half received a combination dose of two monoclonal antibody drugs (casirivimab and imdevimab, both of which have FDA emergency use authorization) between December 2020 and April 2021, while the other half did not. They were all monitored afterward, with their status evaluated two, three and four weeks after treatment.

The results showed a 60%–70% relative reduction in hospitalization among the group that had received the antibodies treatment. The findings suggests that, for high-risk individuals with mild or moderate COVID, "this combination of monoclonal injections gives them a chance of a nonhospitalized recovery," said Raymund Razonable, M.D., a Mayo Clinic infectious diseases specialist and senior author of the study, in a news release. "In other words, they recover safely at home."

At 14 days, 1.3% of the treated group was in the hospital, compared to 3.3% of those who did not receive the monoclonal antibodies treatment. At 21 days, that figure hadn't changed for the treated group — but had increased to 4.2% for those who had not received the treatment.

At 28 days, 1.6% of treated participants were hospitalized, versus 4.8% of the non-treated group.

Monoclonal antibodies, the FDA explains, are lab-created proteins, made specifically to mimic an immune system response. Casirivimab and imdevimab are both designed to target the spike protein of SARS-CoV-2, with the goal of "block[ing] the virus’ attachment and entry into human cells."

Both received emergency use authorization in November of 2020. 

The treatment, from Regeneron, is often referred to as a "cocktail" and before being granted emergency use authorization was used to treat former President Donald Trump as he battled COVID-19.

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The drug combination is not authorized for use in patients who are already hospitalized or require oxygen therapy due to COVID-19. The agency said at the time of authorization that the drug treatment "may be associated with worse clinical outcomes" for patients in those conditions.

But as a short-term treatment for high-risk patients with mild or moderate COVID symptoms, Dr. Razonable sounded optimistic.

"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," he said.

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