The United States Food and Drug Administration on Saturday issued an emergency use authorisation for Regeneron Pharmaceutical’s Covid-19 antibody therapy, an experimental treatment that was administered to President Donald Trump shortly after he tested positive for coronavirus.

The treatment is a cocktail of two powerful antibodies, Casirivimab and Imdevimab, which must be administered together by intravenous infusion. Early studies showed the therapy was effective in keeping the Covid-19 infection in check and reducing medical visits in patients who get the drug early in the course of their disease, FDA said.

“Authorizing these monoclonal antibody therapies may help outpatients avoid hospitalization and alleviate the burden on our health care system,” said Stephen Hahn, commissioner of the Food and Drug Administration.

The emergency authorisation for Regeneron’s drug is, however, limited in scope. It is primarily for those aged 12 and over who have tested positive for the coronavirus and are at high risk for developing severe Covid-19. The drug is not authorised for use in people who are hospitalised or who need oxygen.

Dr George D Yancopoulos, Regeneron’s president and chief scientific officer, said in a statement that he was encouraged by the recent vaccine results, but “there remains a need to treat patients who develop Covid-19, especially as some may not have had access to or were not protected by vaccination”.

Regeneron has received more than $500 million from the US government to develop and manufacture the treatments, according to The New York Times. The company has a contract to provide 3,00,000 doses of the antibody therapy to the US government free of charge.

After Trump received the Regeneron treatment when he was infected with Covid-19, he touted it as a virtual “cure” for the illness, promising to make it free for Americans. But it remains impossible to know whether the antibody treatment helped Trump as he was given multiple medicines.

Two vaccines, one made by Pfizer and the other by Moderna, were recently shown to be more than 90% effective in early analyses. Pfizer, which has completed its trial, submitted an application on Friday for emergency authorisation of the vaccine. Another vaccine candidate developed by the Oxford University and AstraZeneca has produced strong immune responses in older adults in second stage trials.

India has not yet signed a deal for a coronavirus vaccine so it is unclear when it will be available for use in the country, despite some leaders promising it will be available from as early as January. Availability of the vaccine in India would be subject to approval by domestic regulators, and the Indian government agreeing to purchase them.