Dr. Hesham A. Hassaballa, a critical care physician, digs into the data of what happened when a mask mandate was instituted by the governor of Kansas in July. Counties in Kansas were allowed to opt out of the mandate, and dozens of counties did so. Researchers compared the spread of Covid-19 in those counties with the mask mandate and those without and found that in the first two weeks after the mask mandate, cases rose in all counties. However, two weeks later, cases were steady and/or declined. When they controlled for social distancing, they found that the mask mandate decreased transmission between 50% and 61% in those counties that adopted the mandate.
“Now, it is absolutely true that masks do not completely prevent the spread of Covid-19,” writes Hassaballa. “No one has ever said that. It is, however, absolutely true that wearing masks slows transmission of the virus, and we now have real-world data to back this up.”