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New research suggests that a combination of two monoclonal antibodies can be an effective COVID-19 treatment. William Taufic/Getty Images
  • A new study finds that a combination of two monoclonal antibodies can help high-risk COVID-19 patients avoid being hospitalized.
  • In a study involving nearly 1,400 people with mild to moderate cases of COVID-19, significantly fewer individuals receiving antibody treatment required hospitalization.
  • Monoclonal antibody treatments for COVID-19 are most effective when people receive the treatment early, according to some experts.

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A new study from the Mayo Clinic in Rochester, MN, finds that people who contracted the novel coronavirus and are at high risk of developing severe COVID-19 can avoid hospitalization if doctors treat them with a combination of two monoclonal antibodies approved for emergency use by the Food and Drug Administration (FDA).

People with SARS-CoV-2 infection who got the monoclonal antibodies treatment were significantly less likely to require hospitalization than the participants who did not receive the treatment.

This is not the first investigation by the Mayo Clinic into the use of monoclonal antibodies as a means of helping high-risk people avoid hospitalization for COVID-19.

A previous study tested the effect of bamlanivimab, a treatment that had shown promise but whose use, in combination with another monoclonal antibody etesevimab, has been paused due to the emergence of SARS-CoV-2 variants.

Still, lead author of the study, Dr. Raymund Razonable, of the Mayo Clinic, said:

“Once again, this real-world study suggests that when patients who are at high risk due to a range of comorbidities contract a mild or moderate case of COVID-19, this combination of monoclonal injections gives them a chance of a nonhospitalized recovery. In other words, they recover safely at home.”

Avoiding hospitalization may be especially important in the face of current infection rates. Dr. Razonable told Medical News Today:

“Monoclonal antibodies are intended to prevent patients from progressing to severe illness, and this strategy keeps the patients outside the hospital, thereby helping to reduce the burden to the overwhelmed hospital system, especially during the surge period, such as with the ongoing Delta surge.”

The study appears in EClinicalMedicine.

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In the study, doctors treated the participants with casirivimab and imdevimab, a combination the FDA has approved for emergency use.

“Casirivimab and imdevimab are monoclonal antibodies,” Dr. Razonable told MNT, “which are immune proteins that attach to the SARS-CoV-2 spike protein, and this blocks the entry of the virus into the human cells.”

The study tracked 1,400 Mayo Clinic patients who had COVID-19. Of them, 696 received the monoclonal antibodies treatment between December 2020 and April 2021. The remaining participants did not.

The researchers found that after 28 days, 1.6% of the treated group were hospitalized, compared with 4.8% of the untreated group. Overall, the treated group consistently required hospitalization 60–70% less often.

Rates of admission to the intensive care unit and of deaths were low for both groups, making comparisons difficult.

Dr. Tara Vijayan, of the David Geffen School of Medicine in Los Angeles, CA, spoke with MNT about the study and the use of monoclonal antibodies to treat COVID-19. Dr. Vijayan, who was not involved in the Mayo Clinic research, said her own team’s data corroborate the findings of the current study.

Dr. Vijayan said that the casirivimab/imdevimab combination “has been actually quite effective, but […] I think that a lot of this has to do with what variants are out there and how specifically the monoclonals actually work against those variants.”

When asked whether there is any reason to suspect this combination of monoclonal antibodies is not as useful for the Delta SARS-CoV-2 variant, Dr. Vijayan said the treatments seem to be effective against the variant.

Monoclonal antibodies have not been widely deployed to fight COVID-19, although they have been administered to several high-profile patients, including the previous president of the United States, who have recovered successfully from COVID-19.

Dr. Vijayan suspects that their speedy recoveries may be due to the fact that, in general, such people can get treatment immediately after a COVID-19 diagnosis:

“We really think that monoclonals are most effective as early as possible. And, in fact, we now have some evidence that they can be helpful as a prophylactic regimen just after exposure.”

”The only thing that we recommend is monoclonal antibodies for patients who are not [yet] hospitalized,” said Dr. Vijayan. “Timing is everything.”

MNT asked Dr. Razonable about the limited availability of monoclonal antibody treatments. He suggested:

“There are many possible reasons for this, including the logistical difficulty of outpatient infusions in patients who are infectious. There are also a very limited number of studies supporting their use. The antibodies are also not yet fully approved by the FDA, and their use in clinical practice is only based on the FDA emergency use authorization.”

“Educating the public, our patients, and our provider colleagues about the potential benefits of monoclonal antibodies against COVID-19 may help promote their use.”

The new study adds to the evidence that early monoclonal antibody treatments are effective. Dr. Razonable said, “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.”

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