Hence, the original observation, using conventional SCoV2 RBD ELISA, was further analyzed and confirmed by more stringent SCoV2 RBD ELISA, immunoblot analysis, in vitro FCoV2 infection blocking assay with SCoV2 RBD, and, finally, cellular IFNγ immune responses to SCoV2 RBD. Here, IFNG is linked to infection.