BOSTON — Chris Stockbridge knows the power of convalescent plasma as a treatment for COVID-19. He says the treatment may have saved his brother's life and, since he is also a survivor of the virus, he has donated his own plasma to other patients.

He was diagnosed with COVID-19 last spring, suffered few symptoms and had a quick recovery. His brother, however, slipped into a coma before getting the life-saving plasma from another donor.

Sadly, their mother also contracted the virus and died before she could get a plasma infusion.

"How can anybody think twice about giving something that's going to save somebody's life?" Stockbridge asked.

Now, after President Donald Trump announced the emergency authorization of convalescent plasma for COVID-19 patients, the push is on for millions of Americans who have successfully beaten COVID-19 to donate their plasma, too.

The blood plasma, taken from patients who have recovered from the coronavirus and rich in antibodies, may provide benefits to those battling with the disease. But the evidence so far has not been conclusive about whether it works, when to administer it and what dose is needed.

In the authorization letter, Food and Drug Administration officials emphasized convalescent plasma is still under investigation. “COVID-19 convalescent plasma should not be considered a new standard of care for the treatment of patients with COVID-19. Additional data will be forthcoming from other analyses and ongoing, well-controlled clinical trials in the coming months,” the letter said.

Trump made the announcement about the emergency authorization on the eve of the Republican National Convention.