Dynamic changes of throat swabs RNA and serum antibodies for SARS-CoV-2 and their diagnostic performances in patients with COVID-19

Dynamic changes of RNA and antibodies in SARS-CoV-2 infected patients remain largely unknown, and influence factors for antibody production have not been fully clarified In this study, we enrolled 475 cases of COVID-19 and 389 controls Consecutive throat swabs specimens (n=1875) from 187 patients were collected to analyzed the dynamic changes of RNA Moreover, 162 serial serum samples from 31 patients were tested for seroconversion of IgM and IgG Meanwhile, IgM and IgG were also detected in 409 COVID-19 patients and 389 controls Additionally, the logistic regression analysis was executed to identify the possible influence factors for antibody production The median positive conversion time for RNA was day 7 (IQR, 3-11), and the positive rate was the highest in the early stage (74 59 % at day 1-5) and then gradually decreased The median time of seroconversion for IgM and IgG were both day 12 (IQR, 10-15) The sensitivity and specificity for IgM (or IgG) was 87 04 % and 96 92 %, respectively The positive rates of IgM and IgG were both low at the day 1-5 (18 52% for IgM, 14 81% for IgG), and then significantly increased Multivariate logistic regression indicated that reduced lymphocytes and short positive conversion time for SARS-CoV-2 RNA were independent factors for negative results of IgM and IgG tests In conclusion, dynamic changes of RNA, IgM and IgG against SARS-CoV-2, especially antibodies, were unique and they should be combined for COVID-19 diagnosis And antibodies seroconversion was influenced by the decreased lymphocytes and short positive conversion time for RNA