Image of Raymund R. Razonable, M.D., Image credit: Mayo Clinic
Raymund R. Razonable, M.D., Image credit: Mayo Clinic

Results from a new study show that monoclonal antibody treatment lowers the odds of hospitalization by 77% in patients with COVID-19 breakthrough infections, Mayo Clinic investigators say. These SARS-CoV-2 reinfections occur despite prior vaccination and have become more common in long-term care facilities with the rise of the delta variant and as vaccine efficacy wanes for residents who haven’t yet had a booster shot.

Investigators from the Mayo Clinic followed the progress of nearly 1,400 patients who contracted COVID-19 weeks or months after being fully vaccinated against the disease. Some were treated with monoclonal antibody drugs in order to prevent severe illness and hospitalization.

COVID-19 monoclonal antibodies mimic the body’s natural response to infection. Three such drugs in the United States are authorized to be used to treat COVID-19 during the pandemic. Most patients in the Mayo Clinic study were given Regeneron’s drug REGEN-COV (casirivimab and imdevimab), at a median of five days from symptom onset and two days from diagnostic testing. 

Overall, the rate of hospitalization was 2.65% among patients treated with monoclonal antibody, compared to nearly 11% among those who did not receive therapy, the authors reported.

“Early treatment with anti-spike monoclonal antibody was associated with a significantly lower rate of severe COVID-19 that would require hospitalization,” wrote Raymund R. Razonable, M.D., of the Mayo Clinic’s Division of Infectious Diseases.

This was especially evident among the most medically compromised patients, he and his colleagues added.

“Supplementing these patients with monoclonal antibody immunotherapy may have mitigated their risk of clinical disease progression,” they concluded.

The study was published in the Journal of Infectious Diseases.