Role of Serology in the Coronavirus Disease 2019 Pandemic
Sean R. Stowell, Jeannette Guarner
Abstract
In this issue of Clinical Infections Diseases, Xiang et al present a serologic study of 85 nucleic acid test (NAT) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive patients and 24 NAT-negative patients who had symptoms suspicious for coronavirus disease 2019 (COVID-19) Sixty controls were also evaluated and included healthy healthcare staff and patients with a variety of diseases from bacterial pneumonia to lung cancer. Serological testing consisted of an enzyme-linked immunosorbent assay designed to detect immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against the N protein of SARS-CoV-2. Serial examination of COVID-19 patients resulted in IgM seroreactivity by day 4 post-symptom onset, which peaked by day 9. In contrast, IgG sharply increased 12 days after symptom onset; all NAT-positive patients were positive for IgG 30 days post-symptom onset. In patients with suspected COVID-19 who tested NAT negative, IgM antibodies were detected in 87.5% and IgG was present in 70.8%. In contrast, only 3 individuals in the control group tested positive for IgG, but IgM positivity was not observed. The