VISTA is an immune checkpoint protein with suppressive effects on CD4+ and CD8+ T cells.61 In chronic viral diseases (including chronic SARS-CoV-2 infection), exhausted T cells with high expression of VISTA may appear.19 Rendeiro et al found that VISTA was significantly up-regulated in CD4+ and CD8+ T cells in mild and moderate COVID-19 patients. Here, VSIR is linked to COVID-19.