The subset of patients (27%) with severe COVID-19 who developed IgM antibodies against ACE2 (more women, antibodies following infection) are almost certainly not overlapping with the 10% of patients with severe COVID-19 who had preexisting IgG antibodies against type I IFNs (autoantibodies are IgG, almost exclusively in males, preceding infection; ref. 4). Here, ACE2 is linked to COVID-19.