KLK4 and COVID-19: Available drugs used for the management of patients with hereditary angioedema, such as icatibant (a B2R blocker), ecallantide (a small inhibitor of plasma kallikrein), and lanadelumab (a fully human, monoclonal antibody that inhibits active plasma kallikrein proteolytic activity), may be promising candidates that require appropriate evaluation in COVID-19 patients [26,27,161,162,163,164].