Widespread use of face masks in a community can significantly help prevent large outbreaks of Covid-19, according to a study published Tuesday in The Lancet Digital Health.
The study is based on a mathematical model, and looks closely at the association between self-reported mask-wearing, social distancing and Covid-19 transmission.
Overall, the study found that a 10% increase in self-reported mask-wearing could lead to a three-fold increase in the odds of maintaining sufficient control over virus transmission in a community.
“Wearing face masks or face coverings in public spaces has been mandated by governments around the world to try and stem transmission of COVID-19. The aim is to provide a physical barrier that prevents the spread of virus-laden droplets," John Brownstein, senior author of the study, from Boston Children’s Hospital, said in a press statement.
"However, past evidence on the effectiveness of mask use against COVID-19 transmission is mixed and setting up randomized controlled trials to investigate this is challenging," he added.
"Our findings, based on observational data, suggest a community benefit for wearing face masks for slowing the transmission of COVID-19; however, mandates alone may not be enough to increase mask use," Brownstein said. "We recommend that policy-makers consider additional strategies to evaluate and increase mask usage in order to disrupt the ongoing COVID-19 epidemic.”
The study is based on data from self-reported surveys of more than 300,000 people in the US between June 3 and July 27, 2020. Participants were asked to rate how likely they were to wear a mask while grocery shopping or visiting family and friends. The researchers used pre-pandemic data from Google Maps users to make estimates of physical distancing, and then crunched the numbers.
Self-reported mask-wearing was highest among people age 65 and older, as well as Black and Hispanic people. Mask use also varied according to a geographical location, with the highest number of self-reported mask wearers found along the West and East Coasts and southern border, as well as large urban areas.
“An important finding of this research is that mask-wearing is not a replacement for physical distancing and US states the practiced both at high levels had the best probability of controlling disease spread,” coauthor Ben Rader, of Boston Children’s Hospital and Boston University, said in a news release.