Mayo Clinic says convalescent plasma safe, looks promising for treating COVID-19

Researchers at Mayo Clinic gave an update Thursday on the experimental plasma program being used to treat patients with severe cases of COVID-19.

Dr. Michael Joyner, the principal investigator, said new data shows plasma transfusions are safe and the outcomes "continue to look promising."

Mayo Clinic is the lead institution in the Expanded Access Program for COVID-19, sponsored by the U.S. government, collecting and distributing convalescent plasma to patients in need across the country.

"When we started in early April, we thought this would be of interest to people but it’s really taken off like wildfire," Dr. Joyner said.

Mayo Clinic said more than 33,000 people who have recovered from COVID-19 have donated plasma containing antibodies that may help sick patients fight the virus. Nearly 24,000 patients have received plasma transfusions so far.

A new safety report released Thursday looked at data from 20,000 hospitalized patients transfused with convalescent plasma from April 3 through June 11 at health care facilities across the country.

Mayo Clinic said it was a diverse population of patients. About 20% were African American, nearly 35% Hispanic and 5% Asian.

The data shows less than 1% of patients who received plasma had serious adverse side effects.

"That’s really excellent news because that means even the sickest patients can get the plasma without too much worry, or really much worry at all, related to problems stemming from plasma transfusion," Dr. Joyner said.

The report also shows seven-day mortality rates have been declining since early April among patients who received plasma to the current level of 8.6%.

"What does that mean? Well, it could mean a couple things," Dr. Joyner explained. "Maybe we’re giving it to less sick patients, and that’s probably true, but we’re also probably using it in a smarter way. I think the main thing is you want to give it early. It seems to work better before people have prolonged, extreme life-threatening illness."

Dr. Joyner said the mortality rate for patients who received plasma also appears to be "very low" compared to those who did not receive plasma.

He is careful to say the effectiveness of plasma in treating COVID-19 patients is still being studied.

"The physician part of me always wants to be in a position to give people the most hopeful possible message, and I certainly believe I can do that here," said Dr. Joyner. "The scientist part requires me to say, ‘All the information is not there yet. It’s emerging, we’re working on it and we’re attempting to answer these very questions as speak. The efficacy continues to look promising and we may be inching toward being able to make more definitive statements."

Dr. Joyner said they are seeing "interesting case studies" of "nice recoveries" in patients who have received plasma, making it a reasonable treatment for people with very limited options.

"We continue to think about what the next step is and how plasma might be able to help us sort of ‘hold the line’ until vaccines or newer and better drugs are available, hopefully, sooner rather than later," Dr. Joyner said. "This is what we have right now so we have to try to use it in the most intelligent possible way."

Dr. Joyner said, so far, supply appears to be keeping up with demand but he encourages anyone who has recovered from COVID-19 to consider donating plasma. To find the nearest blood blank, click here.