Early in the pandemic, clinicians began to treat people sick with COVID-19 with the plasma of people who have recovered from COVID-19. The idea was that protective antibodies in the plasma would help prevent severe illness and death. Nearly two years later, the evidence is in—and it's being hotly debated. Dr. Arturo Casadevall returns to the podcast to talk with Dr. Josh Sharfstein about the results of the COVID-19 Plasma Project and his take on divergent recommendations about using plasma as a therapy.