For the detection of virus co-expression, both angiotensin I-converting enzyme 2 (ACE2) and transmembrane serine protease TMPRSS2 were required in the testis of COVID-19 individuals, raising concerns regarding the virus entrance from the blood–testis barrier and the presence of COVID-19 in testis tissue and seminal fluid. This evidence concerns the gene TMPRSS2 and COVID-19.