There are actually many factors at play to explain this graph, including: (a) improved treatment and clinical management over time, (b) vaccination, (c) infection-based immunity, (d) survivor bias, as those most likely to die were killed off in earlier waves, (e) increasing denominators with progressive waves, as a lot more people were infected by Omicron and Delta than by earlier variants, especially after vaccination became available, and (f) selective testing bias with earlier waves when testing capacity was limited. Epidemiology is complicated.
All true, but largely D and F. In February of 2020 you pretty much had to be on death's bed to be tested, and today, where I live, the hospital across the street doesn't even stock COVID testing supplies. Magic.
