Cellular Immunity in COVID-19 Convalescents with PCR-Confirmed Infection but with Undetectable SARS-CoV-2–Specific IgG
Sina Schwarzkopf, Adalbert Krawczyk, Dietmar Knop, Hannes Klump, Andreas Heinold, Falko M. Heinemann, Laura Thümmler, Christian Temme, Marianne Breyer, Oliver Witzke, Ulf Dittmer, Veronika Lenz, Peter A. Horn, Monika Lindemann
Abstract
O ne promising therapeutic option to treat se- verely ill patients with coronavirus disease is the use of convalescent plasma (CP) of donors who recovered from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (1-3). When searching for potential CP donors with PCR-confirmed SARS-CoV-2 infection, we observed that 17% of those who volunteered had either borderline or negative results (ratio <1.1) to a SARS-CoV-2 IgG ELISA. We decided to follow up with these volunteers by repeating antibody tests and by assessing T-cell immunity by enzyme-linked immunospot (ELISpot) assay for interferon- (IFN-).