Materials
Three antibody tests were performed: Standard Q COVID-19 IgM/IgG Combo rapid test (SD Biosensor Inc, Suwon, Gyeonggi, Republic of Korea), Platelia SARS-CoV-2 Total Ab (IgM/IgG/IgA) Assay (Bio-Rad Laboratories Inc, California, USA), and Wantai Total Ab (IgM/IgG/IgA) ELISA for SARS-CoV-2 (Wantai Biological Pharmacy Enterprise Co. Ltd, Beijing, China).