PDCD1 and COVID-19: No statistical differences were observed in the tissue immunoexpression of CCR4 (p = 0.845), INF-α (p = 0.637), INF-γ (p = 0.806), iNOS (p = 0.610) and Sphingosine-1 (p = 0.06), nor in number of CD3+, CD20+ (p = 0.533 and p = 0.416, respectively) (Figure 1 and Figure 2) and PD-1+ (p = 0.07) cells in the COVID-19 group when confronted to the H1N1 group.