IFNG and COVID-19: Independently of age and sex, the S1-specific cellular response measured at ER remained as a protective factor (OR per 100 IFN-γ sfu/106 PBMC increment: 0.47, 95%CI 0.20–0.87, p<0.05), while age and male sex appeared as independent COVID-19 severity risk factors (OR: 1.05, 95%CI 1.01–1.10, p = 0.01 and OR: 5.02, 95%CI 1.31–26.07, p<0.05, respectively).