A survey of Chittenden County residents by researchers at the University of Vermont has found that people who wear masks may be more likely to contract COVID-19 because they have more daily contact with other adults.

The study’s lead investigator, Eline van den Broek-Altenburg, an assistant professor and vice chair for Population Health Science at the Larner College of Medicine, said the finding suggests mask-wearers have more interactions with others and “may have a deceptive sense of being protected.”

She said if mask mandates, such as those instituted in Vermont and other states, are not accompanied by proper public education, the practice could lead to more infections.

“Messaging that people need to wear a mask is essential, but insufficient,” she said. “It should go hand in hand with education that masks don’t give you a free pass to see as many people as you want. You still need to strictly limit your contacts.”

The research, by a team of more than a half-dozen health economists and public health faculty, also found that the actual number of COVID-19 cases in Chittenden County may be five times higher than reported. The researchers say 2.2 percent of survey respondents reported they had contracted the virus, suggesting that an estimated 3,621 Chittenden County residents were likely to have become ill, compared with just 662 reported cases.

Van den Broek-Altenburg said that finding shows the importance of random testing of the general population to identify asymptomatic cases, which she says appear to make up the majority of COVID-19 infections.

“If you only test symptomatic patients, you’ll never be able to find out how many people have already had the virus,” ehs said. “With our random sample study we were able to show that Vermont has so far only tested less than one-fifth of the people who have likely had the virus.”

The survey results also suggest that people living in apartments have higher infection rates than people who live in single-family homes.

“If you live in an apartment, you’re going to see more people on a daily basis than if you live in a single family home, so you need to be as vigilant about social distancing,” van den Broek-Altenburg said. 

To create the study group, researchers sent the survey to 12,000 randomly selected people, aged 18 – 70 who had at least one primary care visit at the University of Vermont Medical Center in the past three years. More than 450 people responded.

Van den Broek-Altenburg said the researchers adjusted their models to account for the size of the study group and were able to reach “a high confidence level” in the findings. But more research is needed, she said.

“I hope it leads to other, larger studies that combine survey data with widespread testing. This approach is essential to both understanding the dynamics of this pandemic and planning our response to futures ones,” van den Broek-Altenburg said.

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