The American Red Cross began testing all blood, platelet and plasma donations for COVID-19 antibodies on Monday.
The new test could indicate if the donor's immune system has previously produced antibodies to the coronavirus, whether or not the individual experienced symptoms.
"As an organization dedicated to helping others, the Red Cross is pleased to provide more information about COVID-19 to our valued donors," said Dr. Erin Goodhue, executive medical director of direct patient care with the Red Cross Biomedical Services.
A positive antibody test result does not confirm a COVID-19 infection, Red Cross reminded.
Test results will be available within seven to 10 days in the Red Cross Blood Donor mobile app or through www.redcrossblood.org
Red Cross said there continues to be an urgent need for blood donations, but warned that those who feel symptoms of the corornvirus should postpone their donation.
There continues to be plenty of questions surrounding antibody testing and how to properly use information from them, according to Illinois Department of Public Health Director Dr. Ngozi Ezike.
"It's not clear the level of antibodies that would be protective," Ezike said last month. "So there's, I think there's more questions than answers at this point."
Gov. J.B. Pritzker added that a lot of work has been done surrounding the antibody testing, but a number of them "are ineffectual or not really the kinds of tests that will be used for us."