All of these numbers are likely to be a substantial undercount of the ultimate death toll, since death counting takes time and many states are weeks or months behind in reporting.

But comparing recent totals of deaths from all causes can provide a more complete picture of the pandemic’s impact than tracking only deaths of people with confirmed diagnoses. Indeed, in nearly every state with an unusual number of deaths in recent weeks, that number is higher than the state’s reported number of deaths from Covid-19. Epidemiologists refer to fatalities in that gap between the observed and normal numbers of deaths as “excess deaths.”

Measuring excess deaths is crude because it does not capture all the details of how people died. But many epidemiologists believe it is the best way to measure the impact of the virus in real time. It shows how the virus is altering normal patterns of mortality where it strikes and undermines arguments that it is merely killing vulnerable people who would have died anyway.