Cellular Immunity in COVID-19 Convalescents with PCR-Confirmed Infection but with Undetectable SARS-CoV-2–Specific IgG

• DOI: 10.3201/eid2701.203772
• Publication Date: 2021-01-01T17:25:12Z
• Authors: 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
• Keywords: ELISPOT; Cellular immunity; Humoral immunity; Coronavirus

Abstract We investigated immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among a group of convalescent, potential blood donors in Germany who had PCR-confirmed SARS-CoV-2 infection. Sixty days after onset symptoms, 13/78 (17%) study participants borderline or negative results to an ELISA detecting IgG the S1 protein SARS-CoV-2. analyzed with infection strong antibody (ratio >3) as positive controls and without symptoms household contact infected patients controls. Using interferon-γ ELISpot, we observed that 78% PCR-positive volunteers undetectable antibodies showed T cell immunity similar frequency (80%) T-cell convalescent but did not detect concluded that, IgG, may be mediated through cells.