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How masks helped Hong Kong control the coronavirus

New research shows that universal mask-wearing may help slow the spread of Covid-19.

Pedestrians in Hong Kong wear face masks
Pedestrians in Hong Kong wear face masks as a precautionary measure against the coronavirus on May 14, 2020.
Antony Wallace/AFP via Getty Images

New York City, with a population of about 8.4 million, has had over 28,000 coronavirus deaths as of May 18. Meanwhile, Hong Kong has officially recorded only four Covid-19 deaths, despite having 7.5 million residents.

One reason that could help explain the stark disparity: In Hong Kong, nearly everyone wears a face mask in public.

If any city in the world was likely to experience the worst effects of the coronavirus, Hong Kong would have been a top candidate. The urban area is densely populated and heavily reliant on packed public-transit systems, and it has very few open spaces. Moreover, a high-speed train connects Hong Kong to Wuhan, China, where the coronavirus originated.

Hong Kong, it seemed, was doomed.

But almost as soon as the outbreak first began in the city, millions of residents started wearing masks in public. One local told the Los Angeles Times that the government didn’t have to say anything before 99 percent of the population put them on.

Experts now say widespread mask usage appears to be a major reason, perhaps even the primary one, why the city hasn’t been devastated by the disease.

“If not for universal masking once we depart from our home every day, plus hand hygiene, Hong Kong would be like Italy long ago,” K.Y. Yuen, a Hong Kong microbiologist advising the government, told the Wall Street Journal last month.

“Not wearing masks in Hong Kong is like not wearing pants”

In one way, the ubiquity of Hong Kong’s masks is rather ironic.

Starting last spring, pro-democracy activists took to the streets of Hong Kong to protest a set of laws that would give mainland China — which isn’t supposed to have full control over the city until 2047 — more power over Hong Kong. To protect themselves from police tear gas and avoid the city-state’s ubiquitous surveillance cameras, millions of protesters donned masks.

In an effort to quash the movement last October, Hong Kong’s China-backed government banned the wearing of face masks in public. The hope was that forcing demonstrators to show their faces would make them stay home instead.

Just a few months later, the coronavirus happened.

As the coronavirus first hit the city, Hong Kong Chief Executive Carrie Lam fumbled her response, not wearing a mask during a press conference and, eventually, wearing one incorrectly in public. She also asked government employees not to wear masks.

By April, public health experts in Hong Kong were calling on the government to not only repeal the mask ban but also to mandate the wearing of masks in public as a means of curbing the coronavirus’s spread.

But by then, almost everyone was already wearing them, ban be damned. Indeed, the fact that the government seemed to advocate against masks may have helped make them more popular. Almost in protest, residents started wearing masks in large numbers and helping the most vulnerable communities obtain them.

Hong Kong’s numerous experiences with deadly pandemics also played a role.

The city has faced pandemics before, including the 1968 flu, which began in Hong Kong and killed about 1 million people worldwide. When SARS came to Hong Kong from mainland China in 2003, residents took it seriously and nearly everyone wore a mask. Partly as a result, the city lost only 300 people during that crisis.

Experts say that instilled a sense among the people of Hong Kong that masks are vital to thwarting a pandemic. That sense was reignited when the coronavirus hit. Now they’re everywhere.

“Not wearing masks in Hong Kong is like not wearing pants nowadays,” Alex Lam, a Hong Kong lawyer, told the Wall Street Journal in April.

As the Journal also noted, some taxi cabs and shops won’t let people inside unless they wear a mask. Someone walking around the city without a mask on invites harsh looks from passersby and even verbal reprimands. Even the public address system on Hong Kong’s metro asks riders to wear masks at all times.

Despite Hong Kong’s mask ban officially remaining in place, some of the government’s health officials now praise the citizenry for organically putting the coverings on without being told to do so.

Such praise makes sense, as the latest research indicates that near-universal mask-wearing is critical to fighting the coronavirus.

Masks look like an increasingly important way to curb Covid-19’s spread

It’s worth noting that Hong Kong also implemented a strong testing, tracing, and isolation program, in addition to strengthening travel rules and closing bars at the end of March. Those moves, perhaps just as much as masks, have helped keep Hong Kong’s coronavirus death toll low.

But the masks, research shows, are still very important.

In April, researchers from the University of Hong Kong and the University of Maryland found that masks stopped sick people from spreading Covid-19.

“A mask could catch a lot of the virus a sick person would otherwise be breathing or coughing out,” Ben Cowling, the head of epidemiology at the University of Hong Kong’s School of Public Health and a co-author of the study, told the Wall Street Journal at the time. “Wearing them at least provides some protection for others.”

On May 13, Vox’s Matthew Yglesias also pointed out that in April, researchers at the University of Hong Kong and in Europe calculated that if 80 percent of a population can be persuaded to don masks, transmission levels would be cut to one-twelfth of what you’d have in a mask-less society. However, that study has yet to be peer-reviewed.

On Sunday, another team from the University of Hong Kong determined that the benefits of face masks were massive. Using 52 hamsters in cages, the team found that non-contact transmission dropped by around 75 percent when masks were present. “The findings implied to the world and the public is that the effectiveness of mask-wearing against the coronavirus pandemic is huge,” Dr. Yuen Kwok-yung told reporters.

It does appear, then, that masks are one of the top reasons why the coronavirus situation in Hong Kong isn’t so dire. One wonders whether the rising number of cases and deaths in the US would be lower if Americans similarly adopted such widespread mask-wearing habits.