People who had COVID-19 and are now fully recovered may be eligible to donate plasma to help patients currently infected with COVID-19. Their plasma likely contains antibodies that bind and inhibit SARS-CoV-2, the novel coronavirus that causes COVID-19.

The American Red Cross requires donors to be at least 17 years of age and weigh 110 pounds. Donors who are 17 or 18 have additional weight requirements.

Donors also have to have antibodies that are at a high enough concentration to be helpful for patients. The Food and Drug Administration recommends donors have a SARS-CoV-2 neutralizing antibody titer of 1:160, meaning the antibodies can still be detected even after diluting the sample down to 160th of its original concentration. The agency notes that a titer of 1:80 is acceptable if there aren't any other donated plasma samples with the appropriate blood type available.

Technician looking at donor's plasma

Image source: Getty Images.

The plasma collectors, such as Grifols (NASDAQ:GRFS), will test for antibody levles, but since the antibody tests are in short supply, the plasma collectors prefer to have donations from people who had a positive diagnosis while they were infected to increase the likelihood that the plasma will have antibodies to SARS-CoV-2. But even without a positive diagnosis, it may be possible to get an antibody test for people who weren't able to get a test while they were symptomatic.

Multiple companies testing plasma-based antibodies

In April, CSL Behring (OTC:CSLL.Y), Takeda Pharmaceutical (NYSE:TAK), Biotest, Bio Products Laboratory, LFB, and Octapharma joined forces to develop a plasma-derived antibody treatment. Emergent Biosolutions (NYSE:EBS) is also developing multiple plasma-based treatments of its own.

In the long-term, donations of plasma from patients who have recovered from COVID-19 should result in a standardized product that will hopefully help patients recover from COVID-19.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.