Research Elucidates Duration of COVID-19 Antibodies in CCP Donors

October 19, 2021

A large, nationwide study of COVID-19 convalescent plasma (CCP) donors found that Native Americans and adults aged 55-64 years were more likely to have COVID-19 antibodies for extended periods of time compared with other ethnic and age groups. Amy Schmidt, MD, PhD, from CSL, presented the findings during Tuesday’s oral abstract session on transfusion medicine and cellular therapy.

Schmidt and her co-investigators included data from 418,046 units of CCP collected from 52,240 donors in the study. All plasma donations were screened for nucleocapsid protein-binding-IgG using the ARCH SARS-COV-2 IGG diagnostic method run on an Abbott Architect Analyzer, according to the manufacturer instruction. Results greater than 1.4 Index (sample/calibrator) were considered positive.

The study included donors of various ethnicities aged 18-66 years; 54% were male. Most donors’ antibody levels decreased below 1.40 between 30 and 100 days following their first donation. By approximately 150 days, almost all donors had antibody levels that were essentially undetectable. Younger donors (aged 18-30 years) tended to have lower COVID-19 antibody levels that diminished quickly. Female donors had higher started antibody levels than males (4.28 versus 4.08, respectively), but antibody levels diminished more quickly in females. Investigators also compared initial antibody levels between donors from states with (4.16) and without mask mandates (4.25). While this difference is small, Schmidt said it was statistically significant (p=0.012). There was not a significant difference in the rate of antibody decline.