Wearing face masks reduces the number of times that people touch their faces — particularly their eyes, nose and mouth — in public, a behavioral change that may help prevent the transmission of COVID-19, according to a study published Wednesday in JAMA Network Open.
In countries where mandatory mask-wearing policies were implemented early in the pandemic and where compliance with those policies has been high, the reduction in face-touching has been particularly dramatic. People in China, for example, put their hands to their faces four times less often, and people in South Korea do it six times less often since mask-wearing became mandatory, the study reports.
These findings support those of another, smaller study published online earlier this month. That study found that health care workers in the United States touched their faces four times less often when wearing face masks than when not wearing them.
Health officials believe facial coverings can play an important role in limiting the spread of COVID-19. The major reason is that masks help keep infected airborne respiratory droplets from reaching others. But there’s another possible reason. COVID-19 respiratory droplets can be transferred from someone’s face to other surfaces, such as a handrail or a door handle, via their hands. Someone else may then pick up the virus from the contaminated surface on their hands and, if they touch their mouth, nose or eyes, become infected themselves. By keeping people from touching their face, masks may reduce that risk.
The current study wanted to see just how much face masks lower the likelihood of face-touching behavior.
“An increasing number of governments have enacted mandatory mask-wearing policies for the general population in public areas,” the study’s authors write. “However, the mechanisms of the preventive effect associated with masks are poorly understood, which has contributed to limited public acceptance of mandatory mask-wearing policies.”
How the study was done
For the study, a team of researchers from Sun Yat-sen University in Guangzhou, China, analyzed more than 7,500 videos, gathered from YouTube and other video websites, of individuals from five countries/regions: China, Japan, South Korea, Western Europe (England, France, Germany, Spain and Italy) and the United States. The videos were ones used for tourism or other promotional purposes and took place on streets, in parks and at public transportation stations.
About 4,700 of the videos were taken pre-pandemic (January 2018 – October 2019), while the other 2,800 or so were taken during the early weeks of the pandemic (February 2020 – March 2020). By the time the second set of videos, mask-wearing had increased in all the countries except the United States, although the practice was still rather low in Europe. (Neither Europe nor the U.S. had mandatory mask-wearing policies during February or March.)
The videos used in the study clearly showed the individuals’ faces. The researchers counted face-touching for each video, defined as touching the face with hands, cellular telephones and other items, as well as eating. The areas of the face were divided into the forehead and areas around the eyes, nose, cheek or mouth. None of the individuals was observed for more than one minute.
The videos showed that before the COVID-19 pandemic, the incidence of face-touching was relatively high in the United States, South Korea and Western Europe, and relatively low in China and Japan. In China, the most frequent area touched was the nose, while in Japan it was the cheek. In South Korea, Western Europe and the U.S., the most frequently touched area was the mouth.
During the second set of videos, mask-wearing had increased significantly in China (99 percent of the people in the observed videos, up from 1.1 percent), South Korea (86 percent, up from 3.1 percent), and Japan (39 percent, up from 0.8 percent), but remained low in the U.S. (2.1 percent, up from 0.2 percent) and Europe (1.6 percent, up from 0.4 percent). People in China generally wore surgical masks, while people elsewhere tended to wear cloth ones.
After the pandemic was under way, people in the countries with mandatory face mask policies put their hands to their faces considerably less often than before: 3.9 times less often in China, for example, and 6.7 times less often in South Korea. But reductions in touching of the eyes, nose and mouth — the areas that act as entryways into the body for the COVID-19 pathogen — were even more dramatic. Touching of those areas fell by a factor of 29 in South Korea, by a factor of 11 in Japan and by a factor of 8 in China. No significant changes were observed among people living in Europe or the U.S., however — most likely because so few of them were observed wearing masks in the videos.
Limitations and implications
The study has several limitations. It observed people only in outdoor environments, not in enclosed spaces, such as offices, restaurants and museums. Face-touching behavior might be different in those settings. In addition, the videos taken in South Korea, Western Europe and the U.S. during the pandemic were fewer in number than those taken in China and Japan — a factor that makes country comparisons problematic.
Also, the study does not directly prove that wearing masks mitigates the spread of the coronavirus. “Prospective cohort studies are needed to examine the associations of different types of masks with the prevention of COVID-19,” the study’s authors point out.
Still, the study’s findings are encouraging, for they support — at least in theory — one of the two main ways that masks may help reduce the spread of COVID-19.
“[We] found that mandatory mask-wearing policies increased the mask-wearing rate among the general population during the COVID-19 pandemic,” the study’s authors conclude. “Wearing either a medical or fabric mask was associated with reduced face-touching behaviors, which might prevent transmission of COVID-19 among the general population in public areas.”
Of course, even when wearing facemarks people need to practice social distancing and wash their hands frequently.
FMI: JAMA Network Open is an open-access journal, so you can read the study in full online.