"If you’ve had the virus, if you donate it would be a terrific thing," Trump said during a visit to the American Red Cross headquarters. "We really need donations of the plasma. To those that have had the virus: You’ve gotten through it, and I guess that means you have something very special there."

Convalescent plasma is being studied as a possible treatment for COVID-19. Those who have had the virus and have recovered develop antibodies against the virus in the blood, which could be used to treat those still battling the disease.

https://thehill.com/policy/healthcare/509849-trump-urges-recovered-covid-19-patients-to-donate-plasma