IFNG and COVID-19: According to previous reports, COVID-19 patients at this inflammatory stage of the disease show high plasma proinflammatory cytokines levels (IL-1b, IL-2, IL-4, IL-7, IL-10, MCP-1, GCSF, MIP-1A, TNF-α, IFN-γ and IP-10) [17,18]; however, this fact should not alter the accuracy of the QFT-Plus test since indeterminate results were not due to a high IFN-γ concentration in the nil tube (>8 UI/mL) [8].