Many countries’ coronavirus curves are flattening, at least for now.
Yet somehow, the global case-fatality rate has increased significantly since March, when it was around 3.4%. The rate was 5.8% on Tuesday, according to tallies from the World Health Organization, and it hovered around 7% from mid-April through May.
The trend runs contrary to many experts’ earlier expectations: that testing would increase, leading more mild cases to be recorded and the death rate to go down.
The most straightforward answer may seem to be the case-fatality rate, a calculation of the number of known deaths out of the total number of confirmed cases.
But because coronavirus cases progress over a period of weeks, and because the numbers are constantly changing, the death rate is always in flux.
Some epidemiologists say that because death rates are so heavily influenced by testing and delays in reported cases and deaths, they’re simply not a reliable measure of the virus’s toll over time.