Those who have recovered from the coronavirus have been asked to donate convalescent plasma to help patients fight the virus.

The American Red Cross says it has seen demand for convalescent plasma double as cases rise across the US. The Red Cross says that donations of convalescent plasma are unable to keep up with demand.

The plasma is used for its antibiodies, and while not considered a cure for the virus, it could help patients fight off the disease.

Franklin Miles, a recovered COVID-19 patient, said he learned about the need for convalescent plasma while in the hospital. He said he didn’t know if he would survive.

“It is rewarding to be one of the catalysts to have it, recover from it and can help whether it’s one or 50 people or 100 people,” Miles said.

Miles said he had to wait 28 days to donate, and the process is similar to giving blood. He has donated every 28 days since recovering.

Doctors are still researching the effectiveness of convalescent plasma, but so far, it appears the earlier COVID-19 patients can receive plasma, the better.