Related Articles Profiling Early Humoral Response to Diagnose Novel Coronavirus Disease COVID 19 Clin Infect Dis 2020 Mar 21 Authors Guo L Ren L Yang S Xiao M Chang Yang F Dela Cruz CS Wang Y Wu C Xiao Y Zhang L Han L Dang S Xu Y Yang Q Xu S Zhu H Xu Y Jin Q Sharma L Wang L Wang J Abstract BACKGROUND Emergence of coronavirus disease 2019 COVID 19 is a major healthcare threat Current method of detection involves qPCR based technique which identifies the viral nucleic acids when present in sufficient quantity False negative results can be achieved and failure to quarantine the infected patient would be a major setback in containing the viral transmission We here aim to describe the time kinetics of various antibodies produced against the 2019 novel coronavirus SARS CoV 2 and evaluate the potential of antibody testing to diagnose COVID 19 METHODS The host humoral response against SARS CoV 2 including IgA IgM and IgG response were examined by using an ELISA based assay on the recombinant viral nucleocapsid protein Total 208 plasma samples were collected from 82 confirmed and 58 probable cases qPCR negative but had typical manifestation The diagnostic value of IgM was evaluated in this cohort RESULTS The median duration of IgM and IgA antibody detection were 5 days IQR 3 6 while IgG was detected on 14 days IQR 10 18 after symptom onset with a positive rate of 85 4 92 7 and 77 9 respectively In confirmed and probable cases the positive rates of IgM antibodies were 75 6 and 93 1 respectively The detection efficiency by IgM ELISA is higher than that of qPCR method after 5 5 days of symptom onset The positive detection rate is significantly increased 98 6 when combined IgM ELISA assay with PCR for each patient compare with a single qPCR test 51 9 CONCLUSIONS Humoral response to SARS CoV 2 can aid to the diagnosis of COVID 19 including subclinical cases PMID 32198501 PubMed as supplied by publisher