Patients who had most severe COVID-19 may be best convalescent plasma donors

Healthcare worker holds bag of plasma collected from patient.

Researchers are reporting that patients who had the most severe COVID-19 may be the best donors of convalescent plasma that is increasingly used to treat the disease.

Convalescent plasma contains antibodies to the virus that causes COVID-19 and has been increasingly used by hospitals to treat COVID-19 patients, particularly those with severe cases. It has also been used to help prevent COVID-19.  However, the plasma is used on an experimental basis and is still undergoing testing to verify its efficacy. Studies show that there is significant variability in the antibody responses of COVID survivors, with some having very weak antibody responses that would be ineffective in helping patients.  As a result, doctors are currently seeking guidance for selecting COVID-19 survivors who are the likeliest to have strong antibody responses and make optimal donors.

To find the best plasma sources, the researchers tested the blood of 126 COVID-19 survivors and found high variability in their antibody levels and their antibodies' ability to neutralize SARS-CoV-2, the coronavirus that causes COVID-19. They identified three factors that were associated with stronger antibody responses: having COVID severe enough to be hospitalized; being older; and being male.

Hospitalization status was linked more strongly to a robust antibody response compared to being older and being male, the researchers said. The study could help identify the most suitable donors for obtaining convalescent plasma. The study, funded in part by NHLBI, appeared in The Journal of Clinical Investigation.