In d’Alessandro’s study, KL-6 concentrations measured via two different methods (CLEIA and FEIA) significantly differentiated severe from nonsevere COVID-19 cases, with the Lumipulse G600II showing an AUC of 99.8% and a cut-off value of 448 U/mL, while the AIA360 demonstrated an AUC of 97.4% and a cut-off value of 398 U/mL. This evidence concerns the gene MUC1 and COVID-19.