Recovered COVID-19 patients may hold a key for treating the virus — their plasma.

People who have recovered from the virus develop antibodies that provide immunity. Transferring plasma from someone who’s beaten the coronavirus to a patient currently battling it could help with treatment. Now, Swedish Health Services is working with Bloodworks Northwest to ask people who have recovered to donate.

“Seattle was one of the first epicenters of the pandemic, and with this plasma collection effort, we are one of the first communities to mount an effort at this scale,” Dr. Livia Hegerova, who’s leading a plasma research team at Swedish, said in a news release.

Swedish’s work is part of a clinical trial led by the Mayo Clinic. Earlier this month, the federal Food and Drug Administration authorized plasma treatments for the coronavirus. On April 13, Swedish doctors administered the first plasma treatments in the Northwest.

No health care provider in the region has seen more COVID-19 patients than Swedish, spokeswoman Tiffany Moss said. As of early last week, there were about 100 patients being treated for the virus across all Swedish hospitals, she said.

Transferring plasma from one patient to another is commonly used to treat diseases like the measles and influenza. One donation can treat three to four patients and people can give plasma more than once, according to the release.

Swedish is leading the effort across all of its hospitals and all Providence campuses. Providence Regional Medical Center Everett is taking part in a global trial to treat COVID-19 patients with a drug called Remdesavir, spokesman Casey Calamusa said in an email. The goal is to get 1,000 patients from around the world signed up for the treatment, he said.

Patients who have recovered from COVID-19 and are interested in donating plasma can contact COVID19Study@BloodworksNW.org or call 206-689-6689.