Serological detection of 2019-nCoV respond to the epidemic: A useful complement to nucleic acid testing

Background Pneumonia caused by 2019 novel coronavirus (2019-nCoV) was first reported in Wuhan, Hubei Province, China in December 2019. Then it has been reported in more than 20 countries and regions overseas rapidly. More than eighty thousand cases have been infected, resulting in more than three thousand deaths. Due to the limitation of nucleic acid detection, many clinical suspected cases cannot be diagnosed in time. Methods We used automated chemiluminescent immunoassay to detect serum IgM and IgG antibodies to 2019-nCoV of 736 subjects including confirmed Corona Virus Disease 2019 (COVID-19) patients, non-COVID-19 fever patients, other disease patients and medical staff as well as healthy people. The dynamic process of antibody production in COVID-19 disease progression were analyzed, and the value of antibody detection in the laboratory diagnosis of COVID-19 were evaluated. Results COVID-19 patients were becoming reactive(positive) for specific anti-2019-nCoV IgM antibodies from 7-12 days after the onset of morbidity, followed closely by the IgG. The levels of specific IgM and IgG antibodies increased with the progression of the disease. The trend of IgM and IgG changes in different cases is not exactly the same. The levels of IgM and IgG and their distributions in different groups were different with that of healthy people. The areas under the ROC curves for IgM and IgG to diagnose COVID-19 were 0.988 and 1.000, respectively. Conclusions Specific IgM or IgG antibody detection had good sensitivity and specificity for the diagnosis of suspected fever cases. Detection of specific antibodies in patients with fever can be a good distinction between COVID-19 and other diseases in low epidemic area.