August, 2020
Lincoln – Nebraska Governor Ricketts has, unwittingly, created a "natural experiment" to test the effect of mandated masks on the spread of the coronavirus. Although he threatened to take legal action against a mask mandate in Lincoln and Lancaster County, the local mandate nevertheless went into effect three weeks ago. Conversely, his threats and intimidation of Omaha and Douglas County officials worked. No mask mandate there, although that may soon change.
Natural experiments are often used in evidence-based scientific research when it would be unethical to set up a more rigorous experiment that denied potentially life-saving treatments to a group of participants. Natural experiments are nevertheless valid and, when carefully observed, often considered nearly the equivalent of randomized trials.
Since March, Lancaster County has had a Covid-19 per capita case rate of 52.4 % of that of Douglas County. But in the past seven days (as of August 8), when the effect of Lancaster's mask mandate would be expected to show up, that rate has dropped to 47.4%.
This is not a controlled experiment, of course; no natural experiments are. But its results certainly support a hypothesis that mask mandates matter.*
Governor Ricketts has stubbornly insisted on his view that mask requirements are counterproductive, in that they encourage people to resist them. At the same time, he persists in trying to make hospital bed availability his "North Star" in shaping coronavirus policy. One might ask if assuring Nebraskans that a hospital bed awaits them if they catch the disease is not itself counterproductive to getting them to mask up, voluntarily or otherwise.
The numbers of the natural experiment are sufficiently bracing that the Omaha World Herald has done a front-page article on them. I am also glad to see that the University of Nebraska Medical Center has clearly broken with the governor. It's long overdue. UNMC should never have allowed itself to be misused for political purposes early in the pandemic, when the governor used UNMC personnel as props for his unscientific views. If UNMC wants to compete to become a world-class center to combat infectious diseases, its not helpful to be located in a hot-spot under the influence of a governor who won't be guided by epidemiological evidence.
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* Another natural experiment has happened in Kansas, with even more striking results. See: https://www.wibwnewsnow.com/kdhe-kansas-experiment-shows-masks-work/
Post script August 12, 2020: the Lancaster per capita case rate had fallen further to 36.6% of that of Douglas County on the last day of the Rickett's experiment, before Omaha put in its own mask requirement.
