The emergency use authorization will make plasma and immunology research much harder—not ideal during a pandemic.

In 1901, Italian doctor Francesco Cenci discovered that blood infusions from recovered measles patients could keep other people from getting the illness. A few years later, he discovered that the same treatment helped a critically ill child to recover faster. Similar cases were reported with diptheria, and the treatment was then used in the 1918-19 flu pandemic. Scientists would eventually discover that plasma, the yellowish, watery part of the blood in which red blood cells are suspended, contains antibodies to fight off infection.

On Sunday afternoon, hailing so-called convalescent plasma as a “breakthrough,” President Trump announced an emergency use authorization, or EUA, of the technology for Covid-19. The EUA, which allows a treatment to be used despite not going through the typical tests, will “dramatically expand access to this treatment,” Trump said, calling it a “truly historic announcement.” Read more at The New Republic.