The US Food and Drug Administration on Friday authorised the emergency use of the antiviral drug remdesivir for treating coronavirus disease saying “it is reasonable to believe that its potential benefits outweigh its potential risks” in patients with severe Covid-19.

The FDA said the decision for emergency use of remdesivir was based on a review of topline data from a randomised, double-blind placebo-controlled trial by the US National Institutes of Health and another trial sponsored by remdesivir maker Gilead Sciences that evaluated different durations of treatment.

The authorisation will allow doctors to use remdesivir only to treat adults or children with suspected or laboratory confirmed Covid-19 and severe disease defined by oxygen saturation level of less than 94 per cent on room air, requiring oxygen or mechanical ventilation.

“Based on the totality of scientific evidence available to FDA, it is reasonable to believe that remdesivir may be effective in treating Covid-19, and that when used under the conditions of this authorisation, the known and potential benefits of remdesivir when used to treat Covid-19 outweigh the known and potential risks of such products,” the FDA said in a letter sent to Gilead Sciences.

Remdesivir is an antiviral drug that inhibits synthesis of viral genetic material. The FDA said it is an investigational drug and now currently approved for any indication, but its activity has been observed in cell culture studies and animal models against certain coronavirus infections.

The Indian Institute of Chemical Technology, Hyderabad, a government lab, last week announced a collaborative effort with a pharmaceutical company LAXAI Life Sciences to produce domestic generic version of remdesivir.

Critical care specialists in India said it is too early to predict the impact of the the US FDA decision on emergency use authorisation on India’s policy on the drug. The Indian Council of Medical Research is examining new therapeutic options for Covid-19 patients.

Patients with Covid-19 in India are expected to receive remdesivir as part of global clinical trials.

“The emergency use authorisation opens the way for us to provide emergency use of remdesivir to more patients with severe symptoms,” Daniel O’Day, Gilead chief executive officer said in a statement on Friday.

“We will continue to work with partners across the globe to increase our supply of remdesivir while advancing our ongoing clinical trials.”

Gilead had earlier this week said its trial had found that patients receiving a 10-day treatment course of remdesivir had achieved improvement similar in clinical status to those taking a 5-day treatment course.

The results imply that more patients could be treated with given stocks of the drug.

The company said on Friday it has set a goal of producing at least 500,000 treatment courses by October 1, one million treatment courses by December 2020 and millions more in 2021. These goals were based on the 10-day course. The company said it now anticipates being able to cover significantly more patients based on the trial results showing similar efficacy with 5-day and 1-day durations.

Chinese doctors had earlier this week said their randomized controlled trial on 237 Covid-19 patients had failed to find significant clinical benefit with remdesivir. But the trial, whose results were published in The Lancet, had been terminated midway and the doctors described their findings as inconclusive.