COVID-19 patients
Serum/plasma samples were collected from a total of 99 COVID-19 cases confirmed to be infected with SARS-CoV-2 by real-time RT-PCR (rRT-PCR) on samples from the respiratory tract. These samples were provided by the Biobank of Infectious Diseases (BBEI) of the Institute for Biomedical Research on Retroviruses and AIDS (INBIRS). Seventy-nine of these samples were IgG positive and 20 were IgG negative for SARS-CoV-2 by COVIDAR IgG ELISA test (Laboratorio Lemos S.R.L., Argentina). Sample collection and protocols were approved by the Ethics Committee of BBEI-INBIRS and the Ethics Committee in Clinical Research of the School of Pharmacy and Biochemistry, UBA. All subjects were informed about the purpose of the study, and they signed consent for study participation. Sera were stored at -20°C until assayed.