Antibody responses to SARS-CoV-2 in healthy individuals returning to Shenzhen.

OBJECTIVE: To verify reliability of antibody detection and investigate population immunity to SARS-CoV-2 in the local Chinese population. DESIGN, SETTING, AND PARTICIPANTS: This was a cross-sectional study that was conducted in Shenzhen to detect anti-coronavirus antibodies including, IgG, IgM, and IgA. In the COVID-19 group, 9 patients were enrolled after diagnosis. In the control group, 1589 individuals without clinical symptoms (cough, fever, and fatigue) and returning from outside Shenzhen were enrolled. The first study enrollment occurred at the end of February 2020; the final study visit was March 18, 2020. RESULTS: In the COVID-19 group, the 7 of 9 patients were positive for IgM, IgG, and IgA. Meanwhile, 6 of the 1589 healthy individuals were found to be weakly positive for IgG. According to SARS-CoV-2 nucleic acid tests, the 6 individuals were all negative. CONCLUSION: Strong supplemental support for clinical information can be provided by antibody detection, especially for IgA. According to comparison with overseas reports, the infection rate of the Chinese population outside Shenzhen, China, is significantly low, so most of the population in China is still susceptible. Hence, social distancing measures are still inevitable until a vaccine is developed successfully. This article is protected by copyright. All rights reserved.