The correlation between sCD25 and sPD-L1 levels, the T cell activator and immune checkpoint, in COVID-19 patients, was significant (r = 0.37, P < 0.0001) as well as the relationship between sCD25 and sCD95 (r = 0.46, P < 0.0001) (Appendix Fig. 1). This evidence concerns the gene SPDL1 and COVID-19.