In a recent article in Medical Care, Petersen et al examined the impact of Iowa lifting their state mask mandate in February 2021.
The cumulative case rate in Iowa increased by 20%–30% within 3 weeks of lifting the mask mandate as compared with a synthetic control unit. This association appeared to be related to people, in fact, reducing their mask-wearing habits.
There are three effective classes of people when we think about masking or most other social policies.
- Always Compliers/Always masking — these folks are mandate insensitive.
- Will do it if they have to — these folks are fairly indifferent to a mandate but there is a “taste for compliance”
- Always Defiers/Never masking — these folks are mandate insensitive
There will always be some people who are mandate insensitive no matter what. Their behavior won’t change. Analytically these folks are irrelevant in evaluating whether or not a policy has effect. However the middle group is critical and this is the group where policy leverage exists. If we think that there are a lot of people in this group then there is likely a lot of policy leverage. If we think that this group is pretty small, at least relative to the size of the policy shock that can be delivered, there is not a lot of leverage.
This study finds that there is a lot of leverage. A lot of people will wear masks when there is social and legal sanction behind mask wearing. A lot of people will not wear a mask when the legal sanction disappears and plausibly weakens the social norms and sanctioning of mask wearing.
This leverage led to a lot more people getting infected.