An expert panel from the National Institutes of Health of the United States (NIH) says there is no proven effect of the plasma therapy recommended by President Donald Trump for corona patients.
The food and drug watchdog FDA decided to speed up approval of the therapy, partly after Trump had applied the necessary pressure.
The health authorities state that analysis shows that there is no difference in 7-day survival rates between patients who received plasma with antibodies from recovered patients and those who did not receive the alleged remedy.
The NIH statement is in stark contrast to the claims made by President Trump and FDA chief Steve Hahn at a White House press conference a week ago. There it was stated that plasma therapy could reduce deaths from Covid-19 by 35 percent.
Trump appears to be keen to find a vaccine or cure for the coronavirus before the November election.
A day before the press conference, Trump complained that officials would deliberately delay the development of a drug against Covid-19 to influence the election to his disadvantage. In doing so, the president went so far as to claim that there is a conspiracy against him.
The United States has been the hardest hit of all countries by the new coronavirus. Of the more than 6 million people diagnosed with the infection, 184,320 have died.