US President Donald Trump announced emergency authorisation for a coronavirus treatment involving blood plasma, according to White House officials.
Trump said that the "breakthrough" could result in 35% fewer deaths.
The treatment involves using blood from recovered COVID-19 patients who have built antibodies against the virus and infuse it into people with coronavirus.
But clinical trials have yet to prove the convalescent plasma is effective in treating COVID-19 and it is not known when to administer it and what dose is needed.
The announcement came after days of White House officials suggesting there were politically motivated delays by the Food and Drug Administration in approving a vaccine and therapeutics for the disease that has upended Trump’s reelection chances.
The White House had grown agitated with the pace of the plasma approval, but the accusations of a slowdown, which were presented without evidence, were just the latest assault from Trump’s team on the so-called “deep state” bureaucracy.
Trump tweeted sharp criticism on the process to treat the virus, which has killed more than 175,000 Americans.
“The deep state, or whoever, over at the FDA is making it very difficult for drug companies to get people in order to test the vaccines and therapeutics,” Trump tweeted. “Obviously, they are hoping to delay the answer until after November 3rd. Must focus on speed, and saving lives!”
The White House has sunk vast resources into to develop a vaccine and Trump aides have been banking on it being an “October surprise” that could help the president make up ground in the polls in the November presidential election.
More than 64,000 patients in the US have been given convalescent plasma.