TMPRSS2 and infection: Studies using public single-cell RNA sequencing datasets reported a high expression level of ACE2 and TMPRSS2 in the testis including the spermatogonia, peritubular myoid cells, testis somatic cells, and spermatogonial stem cells [19], but similar studies did not find ACE2/TMPRSS2 co-expression in any type of testicular tissue [20], suggesting that testicular cells do not have a high risk of viral entry and infection and that the impaired testicular function could occur through indirect mechanisms, such as high fever and inflammation promoted by the cytokine storm.