According to the“Diagnostic and treatment protocol of COVID-19 (7th Version)”, the 2019-nCOV IgG/IgM antibody test is one of the proven diagnostic criteria, to assist the diagnostic of COVID-19. This is a big improvement and supplement of PCR assay.

Normally IgM appears at early stage of infection and IgG shows later with an increased titer and could exist in blood for a long time. Regarding how to combine 2019-nCoV IgG/IgM test, the National Center for Clinical Laboratories provides authentic interpretation.