The enzyme-linked immunosorbent assay (ELISA) test system for SARS-CoV-2 IgG from EUROIMMUN Medizinische Labordiagnostika AG (Germany) was used. 
EUROIMMUN Medizinische Labordiagnostika AG
The enzyme-linked immunosorbent assay (ELISA) test system for SARS-CoV-2 IgG from EUROIMMUN Medizinische Labordiagnostika AG (Germany) was used. 
ELISA