Thousands of people received convalescent plasma as an experimental treatment for Covid. A new study shows that it works — but only when given within a few days of the onset of illness.Thousands of people received convalescent plasma as an experimental treatment for Covid. A new study shows that it works — but only when given within a few days of the onset of illness.Coronavirus (2019-nCoV), Blood, Antibodies, Research, Clinical TrialsRead More