Loss of ACE2 might lead to plasma leakage and further activation of the plasma kallikrein-kinin system with more bradykinin formation that could contribute to pulmonary angioedema via stimulation of bradykinin 2 receptors.2 We investigated whether treatment with the bradykinin 2 receptor antagonist icatibant in patients with COVID-19 could be used as a treatment strategy. The gene discussed is KLK4; the disease is COVID-19.