The United States Food and Drug Administration (FDA) has given an emergency authorisation of use of plasma on coronavirus patients.
The technique uses antibody-rich blood plasma from people who’ve recovered from the disease and has already been applied to 70,000 people who were gravely ill in the States.
The FDA says initial trials indicate it is safe, although more are needed to prove effectiveness.
The announcement came a day after President Donald Trump accused the FDA of impeding the rollout of vaccines and therapeutics for political reasons, and on the eve of the Republican National Convention, where he will launch his campaign to win a second term in the White House.
“This is what I’ve been looking forward to doing for a long time,” the president told reporters on Sunday.
“I’m pleased to make a truly historic announcement in our battle against the China virus that will save countless lives.”
Mr Trump described the procedure as a powerful therapy, as he appealed to Americans to come forward to donate plasma if they had recovered from Covid-19.
More than 176,000 people have died from coronavirus, nearly 5.7 million infected since the start of the outbreak in the United States.