It’s difficult to know how many people are dying from COVID-19, mostly because of the lack of adequate testing for the disease, according to epidemiologist Marc Lipsitch of Harvard T.H. Chan School of Public Health.
For example, on April 17, Wuhan, China—where the coronavirus outbreak began—revised upward its number of recorded deaths from the disease by 50%, adding another 1,290 to its toll and bringing its total number of deaths to 3,869. And in the U.S, mortality rates have varied substantially from place to place—for example, the fatality rate in Michigan has been pegged at 7%, about ten times higher than the reported rate in Wyoming.
“Epidemiologists have been pointing to the challenges of estimating the death rate for a long time in this pandemic,” said Lipsitch, professor of epidemiology and director of the Center for Communicable Disease Dynamics, in an interview on WBUR’s “Here and Now” on April 17, 2020. “In the absence of very good testing, and also for some other reasons, we’re going to be undercounting deaths.”
The COVID-19 mortality rate is calculated by dividing the total number of deaths by the number of known cases. But both the numerator and the denominator in that calculation have been uncertain, Lipsitch said. “If you don’t detect mild cases, which nobody is doing … in the U.S., then the denominator is too small, and the death rate looks too big,” he said. “But on the other hand, if you miss deaths, then it would be the other way around.”
Another reason for varying mortality rates across U.S. regions is that different populations have different distributions of risk factors, such as age, hypertension, and obesity, Lipsitch said. Race and income also appear to play a role.
Lipsitch also commented on early reports that the antiviral drug remdesivir may be helping COVID-19 patients in a clinical trial. Lipsitch called the news “encouraging,” but added, “It’s not definitive in any sense,” because the trial doesn’t include a control group that was given a placebo.
If remdesivir does prove to be safe, “it might reduce the severity of the pandemic so that we are less fearful of having people get infected because we have a better treatment,” Lipsitch said. Still, distributing the drug worldwide would pose its own problems. “No drug is distributed equitably around the world even in normal times, and certainly a drug that’s just being ramped up is going to be scarce for some period of time,” he said. “So even if this drug turns out to be promising and a major step forward, it’s not a solution to the pandemic.”
Listen to the WBUR interview: Why It’s Difficult To Assess The Coronavirus Mortality Rate