Mask Mandates and New COVID-19 Cases in September for Nashville

There are 10 counties in the metropolitan Nashville area. Only three of these counties never issued a mask mandate. Of the others, one (Williamson) let theirs expire at the end of August. The other counties all had some form of face-covering requirement for the first three weeks of September. For the 2.5 week period from Sept 5th – 21st, the counties that had a mask mandate in effect experience fewer new cases of COVID-19 than the others. The median increase in new cases for the four counties that did not have mask mandates in place during this period has a median increase equal to 40.6% and three of the four experienced an increase. The six counties with face covering requirements had a median decrease equal to -0.8%, and three of the six saw a decrease in new cases. See the graph below for a county-by-county summary. The bars in red represent counties with no mask mandate during the last 2.5 weeks, while those colored blue indicate counties with a face covering requirement during the same period. Note that the data for each county has been normalized for population so that percentage changes between large and small counties are comparable.

Unfortunately, the county mayor ended the Rutherford county requirement on September 22nd, which will almost certainly result in an increase in new cases in the weeks to come. During the two months with a mask mandate, Rutherford county experienced more than a 50% decrease in new cases of COVID-19. However, you should not stop fighting a fire when it is half out, but when it is completely extinguished. Rutherford, Williamson, and the other counties need to issue mask mandates. Even better would be for the governor to issue a statewide face covering requirement. Alabama experienced a more severe COVID-19 outbreak than Tennessee in the spring, until their governor issue a statewide requirement in mid-July. Now Tennessee’s COVID-19 statistics are worse than its neighboring state.