Prevalence of Severe Acute Respiratory Syndrome Coronavirus-2-specific Antibodies in German Blood Donors during the COVID-19 Pandemic.

Runkel, Stefan; Kowalzik, Frank; Gehring, Stephan; Winter, Julia; Grandt, Caine L; Marron, Manuela; Seifert-Hitzler, Susanne; Hitzler, Walter E

BACKGROUND Coronavirus disease-2019 (COVID-19) is a respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). While RT-PCR assays are used routinely to diagnose active COVID-19, serological testing offers a means of identifying individuals who previously experienced asymptomatic infections, as well as those who experienced symptomatic infections but no longer carry the virus. METHODS The presence of SARS-CoV-2 IgG-positive antibodies in the sera of 673 blood donors residing in south-western Germany before and 3,880 donors after the advent of the COVID-19 pandemic was determined and confirmed using two highly sensitive serological tests. RESULTS Approximately 0.40% of the donors assessed during the COVID-19 pandemic possessed SARS-CoV-2 IgG-positive antibodies, decidedly fewer than the percentage of SARS-CoV-2-infected individuals determined by real-time RT-PCR nationwide. CONCLUSIONS These findings confirm the efficacy serological testing in identifying asymptomatic COVID-19 patients.