If Minnesota’s mask mandate isn’t working, it isn’t because people aren’t complying
Since July 25th, a statewide mask mandate has been in force in Minnesota with the intention of slowing the spread of Covid-19. When he announced it, Gov. Tim Walz said:
“If we can get a 90 to 95% compliance, which we’ve seen the science shows, we can reduce the infection rates dramatically, which slows that spread and breaks that chain”
Nineteen weeks on, how is this working out?
95% of Minnesotans are wearing masks most or all of the time while in public
Data show that Gov. Walz’ ambitions for mask wearing have been met.
Carnegie Mellon Univeristy’s COVIDcast Real-time COVID-19 Indicators report the percentage of people wearing masks based on surveys of Facebook users. As Figure 1 shows, as of November 30th, 94.74% of Minnesotans were reported to be wearing masks most or all of the time while in public.
Figure 1: Percentage of people who wear a mask most or all of the time while in public
There is some variation within the state, as Figure 2 shows, but not very much. While the highest share of mask mandate compliance is found in Hennepin County, with 97.54% of people wearing a mask most or all of the time while in public, the low, recorded in ‘Rest of Minnesota’, is a still impressive 92.28%.
Figure 2: Percentage of people who wear a mask most or all of the time while in public
Minnesota ranks 2nd in new virus cases per capita in two weeks
Sadly, however, while Minnesotans have satisfied Gov. Walz’ ambitions for mask wearing, it has had nothing like the effect he forecast.
Figure 3 shows data from the Minnesota Department of Health on the number of newly diagnosed Covid-19 cases and the share of tests which return positive results. In the seven days up to and including July 24th, Minnesota saw an average of 672 new cases daily and an average rate of positive tests of 4.5%. For the seven days up to and including November 23rd, those numbers were up to 5,874 and 10.7% respectively. Indeed, on Sunday Associated Press reported that ‘Minnesota ranks 2nd in new virus cases per capita in 2 weeks‘.
Figure 3: Covid-19 cases and share of tests positive in Minnesota, seven day moving average
Source: Department of Health
Happily, both of these numbers are now down from their peaks of November 10th for test positivity and November 11th for new cases diagnosed. These peaks, it will be noted, pre-date Gov. Walz’ latest round of business closures and personal meeting restrictions by about a week, which further suggests that policy can only do so much to halt the spread of Covid-19.
Masks work at the margin
It would be bad empirical practice to infer from the above that masks, or mask mandates, don’t work to slow the spread of Covid-19. It might be the case that, without the mandate, case growth would have been even faster. My view is that masks do have some effect in slowing the spread of Covid-19, though the effect is marginal compared to factors like seasonality. This explains why we are seeing surges of cases in neighboring states whether they have mask mandates or not. Even this marginal effect might be enough to justify the minor irritation of wearing a mask, and I do so myself. It is not worth screaming at each other for not caring about others if you don’t.
What is plain is that Minnesota’s mask mandate is not working as Gov. Walz thought it would. To the extent that the mask mandate is the main weapon in the state’s fight against Covid-19, it is probably not up to the task.
John Phelan is an economist at the Center of the American Experiment.