WASHINGTON : 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.