The US health watchdog has given emergency authorisation for the use of blood plasma to treat coronavirus patients in the country, saying the benefits of the treatment outweighed any potential risks. The US Food and Drug Administration (FDA) said on Sunday that over 70,000 patients in the country had been treated with convalescent plasma, which is made using the blood of people who have recovered from coronavirus infections.

President Donald Trump welcomed the move by the FDA on the eve of the four-day Republican National Convention which will renominate him to be the party’s candidate in the November 3 presidential election. “Today I am pleased to make a truly historic announcement in our battle against the China virus that will save countless lives,” Trump said at a White House briefing, referring to the coronavirus that causes Covid-19.

“Today’s action will dramatically increase access to this treatment,” he said, a day after he accused the FDA of impeding the rollout of vaccines and therapeutics for political reasons. In a tweet on Saturday, Trump said “the deep state, or whoever, at the FDA is making it very difficult for drug companies to get people in order to test the vaccines and therapeutics.

“Obviously, the are hoping to delay the answer until after [the US presidential election],” he said. The FDA said in a news release said it has issued an emergency use authorisation (EUA) for investigational convalescent plasma for the treatment of COVID-19 in hospitalised patients as part of the agency’s ongoing efforts to fight COVID-19. Based on scientific evidence available, the FDA concluded, that this product may be effective in treating COVID-19 and that the “known and potential benefits of the product outweigh the known and potential risks of the product.” More than 176,000 people have died from coronavirus since the start of the outbreak in the US, according to a tally by Johns Hopkins University. Nearly 5.7 million cases have also been confirmed nationwide, making America the worst-hit country in the world after the disease emerged in the central Chinese city of Wuhan last year.

“The FDA’s emergency authorisation for convalescent plasma is a milestone achievement in President Trump’s efforts to save lives from COVID-19,” said Health and Human Services Secretary Alex Azar. “Our work on convalescent plasma has delivered broader access to the product than is available in any other country and reached more than 70,000 American patients so far. We are deeply grateful to Americans who have already donated and encourage individuals who have recovered from COVID-19 to consider donating convalescent plasma,” Azar said.

“The data we gathered suggests that patients who were treated early in their disease course, within three days of being diagnosed, with plasma containing high levels of antibodies, benefited the most from treatment. We saw about a 35 per cent better survival in the patients who benefited most from the treatment,” Azar told reporters at the White House briefing. “We dream in drug development of something like a 35% mortality reduction. This is a major advance in the treatment of patients. A major advance,” he was quoted as saying by CNN.

But several experts, including Anthony Fauci, a member of the White House’s coronavirus task force, have expressed reservations about the robustness of blood plasma studies so far. “The problem is, we don’t really have enough data to really understand how effective convalescent plasma is,” Dr Jonathan Reiner, a professor of medicine at George Washington University and a CNN medical analyst, said on Sunday.

“While the data to date show some positive signals that convalescent plasma can be helpful in treating individuals with COVID-19, especially if given early in the trajectory of disease, we lack the randomised controlled trial data we need to better understand its utility in COVID-19 treatment,” Dr Thomas File, president of the Infectious Diseases Society of America, said in a statement. The FDA news release said that based on an evaluation of the emergency use authorisation (EUA) criteria and the totality of the available scientific evidence, the FDA’s Center for Biologics Evaluation and Research determined that the statutory criteria for issuing an EUA criteria were met. The agency said it determined that it is reasonable to believe that COVID-19 convalescent plasma may be effective in lessening the severity or shortening the length of COVID-19 illness in some hospitalised patients. “The agency also determined that the known and potential benefits of the product, when used to treat COVID-19, outweigh the known and potential risks of the product and that that there are no adequate, approved, and available alternative treatments,” the FDA news release said.