When the coronavirus first reached the shores of America, little was known about the power of the mask in preventing the spread of COVID-19, at least among the general public. But over the past nine months, several research studies have measured the effectiveness of mask wearing. The results tell us that by simply wearing a mask, we can significantly reduce the spread of COVID-19 and save many lives.
One such study, by researchers at Carnegie Mellon University and discussed by Christopher Ingraham in The Washington Post, outlined the findings of a state by state look at the relationship between mask wearing and knowing someone in the community who has the virus.
With the help of Facebook, researchers looked at the percentage of citizens within each state who said that they wear a mask in public “all or most of the time” and then correlated that percentage with the percentage of citizens within each state who reported that “they know someone in their community with virus symptoms.” Their thinking was that the more people who state that they know someone with the virus, the higher the rate of the disease within that state.
To test this, we can look at their data and compare it with the infection rate, per state, from other sources like the Centers for Disease Control. For example, North and South Dakota have the highest rate of cases in the nation per 100,000 citizens and, sure enough, in this study have the highest percentage of people (45%) within their states who reported that they knew someone with the virus.
The governors of North and South Dakota have not mandated wearing a mask in public. Thus, in North Dakota, only 72% of the citizens surveyed stated that they wore a mask in public all or most of the time. In South Dakota, it was even lower at 65%. Wyoming had the lowest mask wearing percentage at 63%.
What did the researchers find about these states with low mask-wearing behavior? They found that they also had the highest percentage of citizens surveyed who reported that they knew someone infected with COVID-19. In both North and South Dakota, for example, where self-reporting mask wearing were the lowest, 45% of the citizens reported that they knew someone currently infected with the virus. In Wyoming, the lowest mask wearing state, 36% of the citizens surveyed stated they knew someone infected.
On the other end of the scale, the state with the highest self-reporting mask-wearing behavior, Massachusetts (93%), reported one of the lowest percentages of people knowing someone infected (only 13%). A close second in mask wearing at 92% are the citizens of Connecticut, Maryland, and New York. All of these states had low rates of people knowing someone currently infected (15%, 12%, and 14% respectively).
In summary, this study found a strong relationship, a statistically significant correlation, between self-reporting mask wearing and the percentage of people they knew infected with the virus. My fellow statisticians will remind us that a correlation does not prove cause and effect. True enough. Yet, in fact, sometimes correlational statistics reflect a real cause and effect.
In this study, the r-squared value equaled 0.73. This means that one could predict “about 73 percent of the variability in state-level COVID-19 symptom prevalence simply by knowing how often people wear their masks” according to the study.
The University of Washington’s Institute for Health Metrics and Evaluation recently reported that if 95% of Americans wore masks in public, more than 100,000 lives could be saved from COVID-19 through February. However, they also reported that if our mask-wearing behavior does not improve, the “death toll across the United States could reach about 1 million deaths” by the end of February.
The Institute’s director, Dr. Chris Murray, stated that, “We think the key point here is that there’s a huge winter surge coming and our models have been showing that for many months. You can see [by our research] what universal masks can do and they blunt quite a bit of the surge or delay it.”
As I write this column, additional studies are being published demonstrating the power of wearing a mask in slowing the spread of COVID-19. We can do this, America. For the good of our nation, for the wellbeing of our loved ones and our community, wear a mask when in public. Research has shown that it will save tens of thousands of American lives and help our nation get to the other side of this pandemic.
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Tom Zirpoli is the program coordinator of the Human Services Management graduate program at McDaniel College. He writes from Westminster. His column appears Wednesdays. Email him at firstname.lastname@example.org.