Study participants / Validation cohorts
Between April and October 2020, a cohort of 26 convalescent COVID-19 patients and 14 healthy donors were included in the study in 3 German centres (Berlin, Bochum, Essen). Symptomatic patients with mild to moderate symptoms were eligible to participate at a median time of 48 days after onset of COVID-19 symptoms (during which they become convalescent) according to the WHO management guidance (27 May 2020) and having a confirmed SARS-CoV-2 IgG ELISA at the time of study inclusion. All patients gave written informed consent. The ethical committee of the Ruhr-University Bochum approved the study (20-6886).