S100A12 and COVID-19: An in-sample validation of the seven biomarkers (ApoA1, CRP, ferritin, IL-6, IP-10, SAA1/A2, and S100A12) combined through calculation of a NUM score yielded a sensitivity of 93% (CI: 86 · 5 to 96 · 6) with specificity of 100% (CI: 91 · 0 to 100), applying a cut-off of at least four positive markers in the comparison of COVID-19 patients to healthy controls (AUC: 0 · 99; Figure S5; Table 2).