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Regeneron’s COVID-19 drug appears to prevent virus spread within households

The results come from a clinical trial partly led by a Beth Israel Deaconess Medical Center doctor.

Regeneron Pharmaceuticals headquarters in Tarrytown, N.Y.Michael Nagle/Bloomberg

An antibody cocktail developed by Regeneron Pharmaceuticals provided strong protection against COVID-19 when given to people living with someone infected with the virus, according to the results of a clinical trial partly led by a Beth Israel Deaconess Medical Center vaccine expert.

The results, which were revealed by the Tarrytown, N.Y.-based drugmaker Monday but have yet to be published in a peer-reviewed journal, open another potential avenue to prevent the spread of the virus among people who haven’t been vaccinated.

The late-stage trial found that Regeneron’s monoclonal antibody, which is currently cleared for use for high-risk people who have the disease but aren’t hospitalized, reduced the risk of symptomatic infections in individuals living with someone infected by 81 percent.


Dr. Dan Barouch, coprincipal investigator of the trial and director of the Center for Virology and Vaccine Research at Beth Israel, called the results “highly encouraging.” The treatment, he said, could be particularly useful in places such as nursing homes where residents might be exposed to someone infected with COVID-19 while waiting to get vaccinated.

Barouch helped design the single-dose vaccine from the pharmaceutical giant Johnson & Johnson, the third vaccine authorized for emergency use in the United States by the Food and Drug Administration.

Regeneron’s therapy was given to former President Donald Trump in October after he was diagnosed with COVID-19, but has only been used on a limited basis. It was difficult to administer, requiring an intravenous infusion that took at least 20 minutes. The latest study found that the drug was effective as a simple injection in preventing cases among household contacts.

Regeneron, which jointly tested the drug in a late-stage trial along with the National Institutes of Health, said it will share the data with the FDA and request that the emergency use authorization be expanded.

The study tested the drug on 1,505 people who lived with someone who had tested positive for COVID-19 in the previous four days. Half of the recipients of the injection received the drug, while the other half received a placebo.


“With more than 60,000 Americans continuing to be diagnosed with COVID-19 every day, the . . . antibody cocktail may help provide immediate protection to unvaccinated people who are exposed to the virus,” said Dr. George D. Yancopoulos, president and chief scientific officer at Regeneron.

Jonathan Saltzman can be reached at jonathan.saltzman@globe.com.