The oft-cited “case fatality rate” of the coronavirus has been widely misinterpreted. It is not accurate to assume that a reported fall in the rate means the disease has somehow become less life-threatening.
The rate is calculated by dividing deaths attributed to COVID-19, which is the disease caused by the coronavirus, by the number of cases of infection by the virus. With limited testing, the number of confirmed infections is unreliable. With the disease's unpredictable course, timing and estimates of fatalities are unreliable. The calculations may only be reliably accurate at the end of the pandemic, when everyone infected has either recovered, or died.
Excess mortality rate may be a better representation of COVID-19's impact. This figure compares the number of reported deaths by all causes to what would have been expected in a normal year.