Tennessee counties without mask mandates have a higher COVID-19 death toll per capita, according to a new analysis from Vanderbilt University Medical Center.

The analysis, led by John Graves, PhD, associate professor of Health Policy and director of the Vanderbilt Center for Health Economic Modeling, finds that early adopting counties saw their death rate begin to decline by late July, while later adopting counties saw declines in August and September. Non-adopting counties continue to see death rates rise, the researchers found.

The study uses data on COVID-19 deaths by date of death, not the date the death was reported, which can lag the actual date of death by several weeks. The researchers note because of these lags, Tennessee’s current view of COVID-19 deaths really only represents a clear picture of deaths through the first week of October – meaning that many of the deaths reported each day are tied to infections that occurred in September, before the recent surge in cases of COVID-19 in Tennessee.

“Mask mandates work. Mask mandates are associated with lower death rates. We’ve already shown they are associated with lower hospitalizations rates,” said Vanderbilt Medical Research Professor Melissa McPheeters.

Death rates were initially higher in the areas where masks became required, the analysis found. In the weeks after mask requirements were put in place, areas where masks were required showed sharper declines in deaths per 100,000 population compared to areas where masks were never required.

(Chart below courtesy of Vanderbilt Center for Health Economic Modeling)