Related studies have pointed out that effective drugs to prevent novel coronavirus infection must contain either TMPRSS2 inhibitors or competitive ACE2 binding inhibitors, and it is particularly recommended that bromhexine, a specific TMPRSS2 inhibitor, be used to prevent and treat COVID-19.[21] In addition, several university and institutional experts have jointly published articles to evaluate the importance of TMPRSS2 for respiratory virus infection and introduce the therapeutic potential of bromhexine as a TMPRSS2 inhibitor for COVID-19.[20]. Here, ACE2 is linked to COVID-19.