The Trump administration has granted emergency authorisation for the use of convalescent plasma as a treatment for severely ill Covid-19 patients.

Announcing the move, Donald Trump said the initiative was a “truly historic breakthrough against the China virus” in the treatment of the disease which has claimed nearly 180,000 lives in the US and more than 800,000 globally.

The decision to grant emergency authorisation represents a change of heart by the US Food and Drug Administration, which had previously decided against doing so.

However, the FDA said the decision followed an extensive review of the data collected over recent months.

It added that the benefits of the treatment outweighed any risks.

Experts in the UK have voiced optimism that the technique – which entails infusing a patient with blood plasma from somebody who has recovered from Covid-19 – could prove effective.

“It has had a tremendous rate of success,” Mr Trump added. “Today’s announcement will dramatically increase access to this treatment.”

Mr Trump urged people who have recovered from Covid-19 to donate their plasma to help other patients.

A study carried out by the Mayo Clinic suggested that infusing blood plasma within three days of diagnosis could significantly reduce mortality rates.

But experts, including Anthony Fauci, a member of the White House’s coronavirus task force, have voiced some reservations about the studies.

Concerns over the robustness of the data were heightened after it emerged that the results of the tests – which entailed infusing 66,000 people – were not compared against a control group.

Under pressure over the administration’s handling of the coronavirus crisis, Mr Trump will hope to reap political benefit from any breakthrough.

Last week the president rounded on the Food and Drug Administration, accusing it of impeding enrolment in clinical trials for political purposes.

In a separate development, the Financial Times reported that the administration is also considering fast tracking an experimental Covid-19 vaccine being developed by AstraZeneca Plc and Oxford University for use in the United States ahead of the November 3 elections.

AstraZeneca denied having held discussions with the Trump administration.

“AstraZeneca has not discussed emergency use authorization with the US government and it would be premature to speculate on that possibility,” a spokeswoman for AstraZeneca said in a statement.