TMPRSS2, a transmembrane serine protease, plays a vital role in the entry of respiratory viruses such as SARS‐CoV‐2 and influenza by cleaving and activating viral glycoproteins essential for membrane fusion.[20, 21, 23, 35] We show that Trypstatin effectively blocks TMPRSS2 by binding to the S1 specificity pocket of the protease, thus inhibiting enzymatic activity and thus the cleavage step, thereby preventing viral entry. Here, PSMD1 is linked to influenza.