Antibody Response to COVID-19 Virus — Heilongjiang Province and Gansu Province, China, 2020

WHAT IS ALREADY KNOWN ABOUT THIS TOPIC? Coronavirus disease 2019 (COVID-19) has become a global pandemic, while the profile of antibody response against the COVID-19 virus has not been well clarified. WHAT IS ADDED BY THIS REPORT? In this study, 210 serum samples from 160 confirmed COVID-19 cases with different disease severities were recruited. The IgM, IgA, IgG, and neutralizing antibodies (NAb) against COVID-19 virus were determined. Our findings indicated that four antibodies could be detectable at low levels within 2 weeks of disease onset, then rapidly increasing and peaking from the 3(rd) to 5(th) Weeks. NAb decreased between 5(th) and 9(th) Weeks, and a higher IgM/IgA level was observed in the groups with mild/moderate severity within 2 weeks (p<0.05), while all 4 types of antibodies were higher in the group with severe/critical severity after 4 weeks (p<0.05). WHAT ARE THE IMPLICATIONS FOR PUBLIC HEALTH PRACTICE? Our study on the dynamics of serological antibody responses against COVID-19 virus among COVID-19 patients complements the recognition regarding the humoral immune response to COVID-19 virus infection. The findings will help in the interpretation of antibody detection results for COVID-19 patients and be beneficial for the evaluation of vaccination effects.