Kinetics of SARS-CoV-2 antibodies in COVID-19 patients and relationship with severity of disease

ABSTRACT

Objective To study the kinetics of SARS-CoV-2 antibodies in COVID-19 patients and the correlation with disease severity. Methods A total of 290 plasma samples were collected from 60 hospitalized patients including 48 mild cases and 12 severe cases within 63 days after disease onset in Guangzhou Eighth People′s Hospital affiliated to Guangzhou Medical University during January 21 to April 11, 2020.SARS-CoV-2 specific antibodies were determined by four commercial colloidal gold serologic reagents validated by National Medical Products Administration in China. Results The seropositive rate ranged from 19.23% to 34.62% by four assays within one week after disease onset, and rapidly increased within the following two weeks.The seropositive rates were 52.27% to 68.18% and 83.05% to 98.31%, respectively.IgM antibody peaked within the fourth week and maintained high level for 1 to 2 weeks, and decreased significantly until the 9 th week.But no obvious decreasing trend of the seropositive rate of IgG antibody was observed during two months after disease onset.The seropositive rates of antibodies between mild and severe cases showed no statistical difference.Four assays demonstrated a sensitivity of 78.33%to 91.67%in 60 COVID-19 patients.The difference was statistically significant between the highest and the lowest values（χ2=4.183,P=0.041）． Conclusions The colloidal gold serologic reagents show good sensitivity during the late stage of disease but not at the early stage.There is no correlation between seropositive and disease severity.The sensitivity of different reagents is different