RT-PCR Status and Antibody Response in Patients with Coronavirus Disease 2019

Abstract Background: Novel coronavirus (COVID-19) is a new viral species that causes pneumonia. Currently, RT-PCR and IgM/IgG antibody assays have been recommended for the diagnosis of COVID-19 infection. However, the correlation between RT-PCR status and antibody (IgG, IgM) response remains unknown. Methods: Consecutive COVID-19 patients admitted to our department between February 10, 2020 and March 10, 2020, were diagnosed by guidelines issued by the World Health Organization (WHO) and included in this study. RT-PCR and antibody (IgM/IgG) assays for COVID-19 infection were performed for all patients according to the manufactures’ protocols. Other data, such as demographic, clinical, laboratory, as well as treatment and outcome, were collected using data collection tables from electronic medical records.Results: During the study period, a total of 103 patients were diagnosed as having a moderate type of COVID-19 at our department, including 55 males and 48 females, with an average age of 57.53 ± 1.65 years old (range 23 to 90 years old). The peak level of SARS-CoV-2 IgM antibody (243.10 ± 89.84 AU/ml) was reported 4 days after the negative RT-PCR (-) (all P < 0.05). Subsequently, the IgM decreased to 42.69 ± 22.39 AU/ml 21 days after RT-PCR (-). However, the IgG was maintained at a high level 4 days before RT-PCR (-) and later. The lymphocyte count was at the lowest level on day7 before the RT-PCR(-) result (P<0.05), and then elevated after RT-PCR conversion (viral clearance).Conclusions: SARS-CoV-2 IgM/IgG levels did not correlate with RT-PCR status in our study sample. We found that SARS-CoV-2 IgM/IgG could be a potential biomarker to monitor clinical course, determine discharge, and assess recovery of those infected patients with the novel coronavirus. Trial registration: A prospective, open label, randomized, control trial for chloroquine or hydroxychloroquine in patients with mild and common novel coronavirus pulmonary (COVIP-19). ChiCTR2000030054. Registered 18 Feb,2020. http://www.chictr.org.cn/edit.aspx?pid=49869&htm=4