Evaluation the auxiliary diagnosis value of antibodies assays for detection of novel coronavirus (SARS-Cov-2) causing an outbreak of pneumonia (COVID-19)

Yong Gao; Yi Yuan; Tuan Tuan Li; Wu Xiao Wang; Yong Xiu Li; Ang Li; Feng Ming Han

The copyright holder for this preprint . https://doi.org/10.1101/2020.03.26.20042044 doi: medRxiv preprint and preventive quarantine. The human immune system can produce specific IgM and IgG antibodies against virus infection. IgM is the earliest antibody that appears upon first immune response. Serological presence of IgM indicates a recent infection and could be used as auxiliary diagonosis of early infection. IgG is produced later and lasts long, which can be used as an indicator of previous or secondary infection (18) (19) . In this study, the positive rate of throat swabs was only 13.0% for cases in later phase( ≥ 15 d.a.o), and the sensitivities of IgM and IgG were 52.2% and 91.3%, respectively. Combining use of antibodies assay at the same time could be able to greatly improve the sensitivities of pathogenic-diagnosis for SARS-CoV-2 infection, especially for the throat swabs group during the later stage of illness.Moreover, through further analysis of the antibodies test data of cases with undetectable viral RNA in throat swabs specimens at the early stage of illness, we suggest that most of these cases could be IgM/IgG seropositive after 7 days of negative nucleic acid test results, indicating an auxiliary diagnosis value of antibodies assays.