The US Food and Drug Administration (FDA) has given emergency authorisation to use plasma to treat Covid 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 in the US – in trials or for the gravely ill. The agency said it had concluded it was safe after reviewing the results of 20,000 patients who had received the treatment so far. The FDA said people under the age of 80 who were not on a respirator and received plasma containing high levels of antibodies had a 35% better survival rate a month after the treatment than those who had received plasma with a low level of antibodies. Mr Trump has 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.