Given that sULBP2 is a surrogate marker of ULBP2, which is present on the surfaces of virus-infected cells (8), it can be inferred that the rise in inflammatory cytokine levels and the expression of molecules that activate NK cell function occur simultaneously during the acute phase of moderate COVID-19 (Figure 7B) (28, 29). The gene discussed is ULBP2; the disease is COVID-19.