
Once Americans return to crowded offices, schools, buses and trains, so too will their sneezes and sniffles.
Having been introduced to the idea of wearing masks to protect themselves and others, some Americans are now considering a behavior scarcely seen in the United States but long a fixture in other cultures: routinely wearing a mask when displaying symptoms of a common cold or the flu, even in a future in which Covid-19 isn’t a primary concern.
“I will still feel a responsibility to protect others from my illness when I have a cold or bronchitis or something along those lines,” said Gwydion Suilebhan, a writer and arts administrator in Washington who said he also plans to continue wearing masks in situations like flying on airplanes. “It’s a responsible part of being a human in a civil society to care for the people around you.”
Such routine use of masks has been common for decades in other countries, primarily in East Asia, as protection against allergies or pollution, or as a common courtesy to protect nearby people.
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Other leading American health officials, however, have not encouraged the behavior. The Centers for Disease Control and Prevention — which at the beginning of the pandemic advised against wearing masks, and only changed its guidance a couple of months later — does not advise people with flu symptoms to wear masks, and says they “may not effectively limit transmission in the community.”
That’s partly because there’s no tidy scientific consensus on the effect of masks on influenza virus transmission, according to experts who have studied it.
Nancy Leung, an epidemiologist at the University of Hong Kong, said that the science exploring possible links between masking and the emission or transmission of influenza viruses was nuanced — and that the nuances were often lost on the general public.
randomized controlled trials — the gold standard in scientific research — that masking reduced transmission of influenza viruses in a community.
There was some evidence from observational studies that masks reduced community transmission of influenza viruses, she added, but that research had a caveat: Observational studies cannot isolate masking from other possible factors, such as hand hygiene or social distancing.
“You can’t really decipher whether that observed reduction in transmission is due to face masks alone or not,” Dr. Leung said.
For similar reasons, the fact that the flu all but vanished in the United States during the coronavirus pandemic — and that many Americans anecdotally reported that they caught fewer colds than usual in 2020 — is not evidence alone that masks were responsible.
In East Asia, the historical use of masks is based on more than just medical research, and the steps that led each country to adopt them vary widely.