Blood immunity

In the early 70's the poultry industry was hit hard by a virus called leukosis. About 12% of all chickens were discarded at the plant by USDA inspectors. Ralston Purina injected turkeys with the virus and found it was not harmful to turkeys but they then injected baby chicks with the turkey blood and the chicks were immune to the virus. This procedure is now being tested with the coronavirus. Blood from people who have recovered from the virus is being injected to people who have not had the virus to see if it will provide immunity.