A study published Wednesday by scientists in the U.K. finds that widespread adoption of face masks, in addition to lockdowns, could prevent further waves of the coronavirus and allow for less strict lockdown measures.
The researchers, who hail from Cambridge University and Greenwich University, argue that lockdowns alone are not sufficient to prevent second and third waves of infection, but if “combined with 100% adoption of face mask use by the public,” infection rates can be flattened and subsequent waves can be prevented.
The researchers looked at four models to see how effective masks could be in lockdown scenarios: one where no one wears face masks, one where 25% of the population wears masks, one where 50% is masked, and one where everyone is masked. In each one, there are intermittent lockdown periods.
In the first scenario, in which no one wears masks, infections increase exponentially, slightly slowed by the first lockdown; a second wave starts when the first lockdown ends. In the second scenario, in which a quarter of people wear masks, the first three infection peaks are flatter, and “there are clear benefits to face mask wearers, compared with non-wearers,” with the former recording many fewer infections.
In the third, in which half the population wears masks, infections barely increase at first but then start to take off in the fourth lockdown period, and infection rates are lower among mask wearers.
“When 100% of the public wear face masks, disease spread is greatly diminished,” the researchers wrote in the study, which was published in the scientific journal Proceedings of the Royal Society A.
The research suggested that any kind of face mask—including homemade coverings and ill-fitting masks—”is likely to decrease viral exposure and infection risk of a population level,” and the more people wear masks, the better.
The researchers focused on the U.K., where government guidance on face masks has not been consistent, and they called for “the widespread adoption of face masks.” At the time of writing, the researchers noted, only Scotland had recommended public use of face masks; the rest of the U.K. had not made any recommendations.
Face masks will become compulsory in England on June 15, but only for people on public transport. Wales on Tuesday advised people to wear face coverings when on public transport or in crowded areas, but emphasized that wearing masks on public transit will not be compulsory. In the U.S., the debate over face masks has morphed into a culture war.
Meanwhile, many Asian nations saw mass adoption of masks early in the COVID-19 crisis, and the practice is credited with slowing the disease’s spread.
Researchers at the University of Hong Kong (HKU) wrote a separate paper assessing the influence of different public health measures on virus suppression in Hong Kong, which flattened its first wave and squashed a second. A preprint of the paper came out on Tuesday.
Hong Kong “stopped short of a society-wide lockdown,” the researchers wrote. This differs from the U.K., which has been on lockdown since March 23.
The HKU researchers “could not directly estimate the effectiveness of some important interventions, such as face mask wearing,” but said a combination of measures including face masks, contact tracing, and physical distancing helped to prevent subsequent waves of infection in Hong Kong.
“It is likely that the widespread use of face masks in the community has played a role in reducing transmission,” the HKU researchers wrote, noting that the largest infection clusters in Hong Kong occurred in bars and at a wedding dinner, “both locations in which face masks were not worn.”