T cells from COVID-19 patients have markedly higher expression of PD-1 and Tim-3 and produce significantly higher levels of TNFα, IL-6, and IL-10; such upregulation of PD-1 and Tim-3 positively correlates with disease severity in patients, while elevated levels of cytokines negatively correlate with T-cell counts.78 The gene discussed is HAVCR2; the disease is COVID-19.