CD40LG and infection: In another study evaluating the Abbott SARS-CoV-2 IgM and IgG assays in 300 control samples and 1349 sequential samples from 427 RT-PCR positive patients [14], the clinical test sensitivity of the IgM and IgG assay was 24.6% and 23.2% in the first week of infection, and the positive rate was 30.8% and 92.3% at >3 months later.