By the time the novel coronavirus was declared a pandemic in March, masks were already ubiquitous in parts of Asia that were closest to the then-epicenter in Wuhan, China.
“Even going back to January, people in Hong Kong started wearing face masks, and by the end of January, we had 99% of people wearing face masks in the community,” recalled Ben Cowling, an epidemiologist and biostatistician at The University of Hong Kong.
Cowling said memories of previous deadly outbreaks of SARS and MERS were still fresh in the region, and people quickly reached for masks as the new coronavirus crept in.
In other places around the globe, however, masks haven’t been readily embraced. Mixed public health messages early on, hastily published research, and the politicization of masks have contributed to confusion and resistance in some places.
But the more researchers are learning about SARS-CoV-2, the virus responsible for COVID-19, the more the evidence points to the importance of face coverings in limiting its spread in communities across the globe.
Cowling has been studying the effectiveness of masks against respiratory illnesses like seasonal flu and different strains of viruses in the coronavirus family for years.
In the lab, Cowling runs tests using a machine with an inverted cone on it — sick people breathe into it with a mask on.
“And what we found is that surgical face masks do a really good job, they’re not perfect, but do a really good job of reducing the amount of virus that comes out. So, that means if infected people were wearing face masks in the community, there’d be a lot less potential for transmission.”
“And what we found is that surgical face masks do a really good job, they’re not perfect, but do a really good job of reducing the amount of virus that comes out,” he said. “So, that means if infected people were wearing face masks in the community, there’d be a lot less potential for transmission.”
Masks may also protect against exposure, too, he said.
It was clear in March that the pandemic had hit the US, but health leaders discouraged widespread use of masks. They later said they worried about a run on the medical-grade masks so urgently needed in hospitals.
Then in early April, as it became more apparent that people could be infected with the new coronavirus and not show symptoms, the Centers for Disease Control and Prevention started recommending the public wear masks, even fabric ones.
The US Surgeon General Jerome Adams hosted a DIY mask-making video.
“It’s that easy,” he explained, after folding over the fabric of an old T-shirt.
President Donald Trump has famously not worn a mask when out. Last weekend in Tulsa, Oklahoma, as he took the stage at his campaign rally, he told people who wanted to come to “do what they want.”
There have been mixed messages in other nations, too. In April, French President Emmanuel Macron assured the public that everyone would soon be able to get a general-purpose mask.
But this came after health leaders first said that only people who were sick or worked in health care needed to wear them.
It wasn’t until early June that the World Health Organization issued its clearest mask guidelines for the public.
“WHO advises that governments should encourage the general public to wear masks where there is widespread transmission and physical distancing is difficult.”
“WHO advises that governments should encourage the general public to wear masks where there is widespread transmission and physical distancing is difficult,” Director-General Dr. Tedros Adhanom Ghebreyesus said in a June 5 briefing on the matter.
The agency released updated videos on best practices for mask-wearing and put out a range of tips: Fabric masks should “ideally be made with three layers of fabric. The outer layer should be a water resistant fabric.” A mask should be snug over the chin, cheeks and nose, and one should wash hands before putting it on and before taking it off.
WHO also stressed that masks shouldn’t be seen as a replacement for other important physical distancing and hygiene measures.
Masks can ‘do a lot of good’
The agency has faced criticism for waiting so long to recommend widespread mask use, but Julie Leask, a professor at the University of Sydney's School of Nursing, said a certain amount of confusion is to be expected with a new disease threat.
“Inconsistency and pandemics or health emergencies go hand in hand, it’s inevitable.”
“Inconsistency and pandemics or health emergencies go hand in hand, it’s inevitable,” said Leask, who specializes in risk communication and infectious disease prevention behaviors. She has also consulted for WHO.
“Because you’re dealing with uncertainty, particularly at the beginning of an emergency, the evidence on how COVID-19 is transmitted when you’re infectious — all of that is still being established.”
WHO may be slow in issuing recommendations, she said, because they have to weigh a lot of factors, which can vary across countries and communities.
“Their recommendations have to consider a whole range of different contexts, and particularly low- and middle-income countries that may have limited supply of masks [and] may have different background rates of COVID-19 transmission in the community,” Leask said.
WHO, in part, made its recommendations after a review of 172 mostly observational studies on masks and other public health measures. It found that face masks can be protective for health care workers and people in community settings who are exposed to infection, but that “more robust research,” like randomized controlled trials, are needed to better inform guidelines.
Such trials — where some people wear masks and others don’t — are especially challenging during a pandemic, said Dr. Elie Akl, a professor of medicine and epidemiology at the American University of Beirut in Lebanon.
Akl, who is part of the COVID-19 study group assessing the evidence for masks, social distancing and other measures, said research on surgical and N95 masks in health care settings is stronger. When it comes to the fabric ones: “I think they’re probably effective to some extent,” he said. “Particularly for source control. So, if you have someone who might be infected, whether symptomatic or not, this might help reduce the transmission.”
Cowling, the epidemiologist in Hong Kong, also hopes the science around mask use and the coronavirus will become even clearer with more research.
In the meantime, he suggests people wear a mask, even if it’s not a medical-grade one.
Not all masks are perfect, “but we can use them because they still do some good,” he said. “And we shouldn’t say that 'masks aren’t perfect, therefore they’re no use' because actually imperfect masks can still do a lot of good in public health.”