By contrast, co-inhibitory receptors, such as CTLA4, CD274 (PD-L1), PDCD1 (PD-1), LAG3, and HAVCR2 (TIM-3), working together with IL-10, have been reported in acute viral infection, such as SARS-CoV-2 or influenza virus, playing a double role, one limiting inflammation induced tissue damage and ALI, as can particularly be the case for the virulent Lena strain, and another one, inducing a progressive dysfunction of T cells, impairing viral clearance and leading to chronic infection (33, 77, 79). Here, PDCD1 is linked to viral infectious disease.