"ACE2 has been shown to be the entry point into human cells for some coronaviruses, including the SARS virus. A number of studies have identified that the entry point is the same for SARS-CoV-2, the virus that causes COVID-19.

This might lead some to suggest that decreasing the levels of ACE2, in cells, might help in fighting the infection, but that conflates ACE2 with the ACE2 receptor. More interestingly, ACE2 has been shown to have a protective effect against virus-induced lung injury by increasing the production of the vasodilator angiotensin 1–7. In fact, the interaction of the spike protein of the virus with the ACE2 induces a drop in the levels of ACE2 in cells, possibly inducing lung damage. Claims that the available (AT1R) blockers (Angiotensin II receptor blocker) such as losartan, can help in curing COVID-19 need to be tested by datamining of clinical patient records. Suggestions that high dosage of Vitamin D, which has been shown to increase expression of ACE2 in cells, could be effective in fighting the infection should be studied.[according to whom?] A possible way of combating the infection could be the injection of soluble ACE2 into the blood stream which will have the twofold effect of competing with cellular ACE2, preventing the attachment of the virus to non-infected cells and replenishing ACE2 in infected cells. (...)"

From https://en.wikipedia.org/wiki/Angiotensin-converting_enzyme_2