It’s time to wear a mask again, health experts say

Masks are back, and, this time, they’re not just for Covid-19. A “tripledemic” of the coronavirus, influenza and respiratory syncytial virus, known as RSV, sweeping through the United States has prompted several cities and counties, including New York City and Los Angeles County, to encourage people to wear a mask in indoor public spaces once again.

Nationwide, Covid-19 case rates have spiked by 58 per cent since the end of November. The Centres for Disease Control and Prevention estimates that there have already been 15 million illnesses and 9,300 deaths from flu this season, and those numbers are expected to rise in the coming months. (Over the past decade, annual flu deaths have ranged from 12,000 to 52,000 people, with the peak in January and February.) And while RSV finally appears to be on the decline, infection rates are still high across much of the country.

The CDC officially advises wearing a mask on a county-by-county basis depending on community Covid-19 levels, which take into account virus-related hospital admissions, bed capacity and case rates. However, in an interview with NPR this month, Dr Rochelle Walensky, the CDC director, said, “You don’t need to wait for CDC’s recommendation, certainly, to wear a mask.”

Rates of Covid-19, flu and RSV “may be more intense or a little bit less intense in some parts of the country, but really, the entire country is being affected,” said Dr William Schaffner, a professor of preventive medicine at the Vanderbilt University School of Medicine. He urged anyone who lives in a high-risk household to “put your mask back on” when in public spaces. High-risk households include those with adults over the age of 65, pregnant women, people with a preexisting condition such as heart disease, diabetes or lung disease and anyone who is immune-compromised.

Dr Helen Chu, an associate professor of allergy and infectious diseases at UW Medicine in Seattle, went a step further, recommending everyone mask while infection and hospitalisation rates are so high. “I think it’s a good time to mask,” she said. “Given where we are right now with hospitals being at very close to capacity, especially in pediatric hospitals with RSV and with flu, I think that anything that you can do to slow down community transmission is going to be helpful.”

There is good evidence that masks help to reduce the transmission of respiratory viruses. One paper published in 2020 by researchers in Hong Kong showed that people sick with Covid-19 or the flu breathed out fewer viral particles when they were wearing a surgical mask. (Masks were found not to be as effective for the rhinovirus, which causes the common cold.) A study of Covid-19 policies in Boston-area schools found that removing a mask mandate in 2022 was tied to nearly 12,000 additional cases among students and staff members.

Rates of influenza and other respiratory viruses essentially flattened during the 2020 and 2021 winter seasons, which was largely attributed to the protections the country took to prevent the spread of Covid-19. “What Covid has shown us, because we’ve been social distancing and mask wearing, is that influenza, the common cold viruses, RSV are suppressed remarkably” by these small individual behaviors, Schaffner said.

Masks work by filtering the tiny aerosol particles through which the coronavirus is primarily spread and the larger droplets that are thought to be responsible for most influenza and RSV transmission. They also stop you from touching your face in case you picked up virus particles on your hands. And while masks are most effective at stopping the spread of these viruses when the infected person is wearing one, masking to protect yourself from disease is still beneficial, particularly if you’re using a high-quality version like N95, KN95 or KF94.

This article originally appeared in The New York Times