CD40LG and COVID-19: Moreover, the overall sensitivity of IgG for the identification of COVID-19-positive patients was 80.0% (27.7% for IgM), the specificity was 94.3% (91.4 for IgM), the NPV was 71.7% (40.5% for IgM), and the PPV was 96.3% (85.7% for IgM).