
By BY CARL ZIMMER from NYT Health https://ift.tt/34FSnrs

A century before COVID, a doctor came up with the idea of using face masks to stop a deadly plague in China.
Some scientists have questioned both the timing of the approval and the veracity of a key survival statistic cited by FDA Commissioner Dr. Stephen Hahn. And the clinical trials needed to make sure that convalescent plasma really works are not yet complete.
Experts warned that the revised CDC guidelines could delay treatment and lead to wider spread of the coronavirus.