IFITM3 and viral load: In addition, the activity of TMPRSS2 affects the function of Interferon-induced transmembrane protein 3 (IFITM3), which was identified as a potentially relevant factor in the control of SARS-CoV-2 infection, due to its known involvement in other viral diseases, as well as to its interaction with S protein (Prelli Bozzo et al., 2021[41]; Shi et al., 2021[51]).