Will one-way masking stop Covid spread? Here’s what experts say.

States across the U.S. are moving to end some indoor mask mandates as Covid-19 cases from the omicron-fueled surge continue to subside.

California, Connecticut, Delaware, New Jersey and Oregon and other states are rethinking mask mandates for public spaces and schools, as many Americans say they are tired of masking indoors. Masking was once considered an essential tool to prevent the spread of Covid to others, but pandemic strategies have shifted as more vaccines and treatments have become available and the country has begun moving toward a “new normal.”

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Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, said Wednesday that the agency is working on updated guidance for masking, noting that much of the country is still seeing high or substantial transmission.

"We're evaluating rates of transmission as well as rates of severe outcomes as we look at updating and reviewing our guidance," she said at a White House Covid-19 Response Team briefing.

Though most health experts agree universal masking, along with vaccinations, remains the best public health strategy against the spread of the virus, people can still benefit from wearing a mask even if no one else around them is.

"You're certainly much better protected than you would be if you're not wearing a mask at all," said Lawrence Gostin, a professor of public health at Johns Hopkins University and director of the World Health Organization Collaborating Center on National and Global Health Law.

However, since the omicron variant is so contagious and still spreading so widely in the U.S., protection from a mask may be a bit less, regardless of one's vaccination status, said Cheryl Healton, dean of the New York University School of Global Public Health.

"Those not wearing masks can transmit Covid-19 to them, and they can, in turn, transmit to others," Healton said.

A mask should still provide some protection in an unmasked setting, assuming it's well fitted and worn correctly, said Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health.

Image: Wall Street Stock Exchange (Star Max / AP file)
Image: Wall Street Stock Exchange (Star Max / AP file)

The CDC has advice on its website for properly wearing a mask, saying it should cover one’s nose and mouth and be secured under the chin.

The type and quality of the mask matters, too. A CDC study released Friday found that people who consistently wear a high-quality mask, such as an N95 or KN95, in an indoor public setting appear to have the best chance of avoiding Covid. The CDC report looked at randomly selected California residents who had received either a negative or a positive Covid test from Feb. 18 to Dec. 1.

It found that when someone wore a cloth mask, the odds of testing positive for Covid infection were reduced by 56 percent. A surgical mask lowered the odds by 66 percent. People who wore an N95 or KN95 were 83 percent less likely to test positive for Covid.

The report came weeks after the agency updated its guidance on masks for the general public, saying people “may choose” to wear N95 and KN95 masks because they offer the best protection against this virus.

An N95-caliber mask can “provide you with as optimal protection as possible irrespective of what those around you are doing,” said Ranu Dhillon, an epidemic response specialist at Harvard Medical School.

The masks are so good because of the way the fibers are arranged and because they usually contain an electrocharged layer that can neutralize the virus coming in or out of the mask, he said.

Wearing an N95 allows people to "live as normally as possible but still stay safe," Dhillon said. Some people find N95 masks uncomfortable to wear, he said, but “there’s an array of N95 masks you can find that are actually more comfortable than the surgical or cloth masks.”

Gostin, of the World Health Organization Collaborating Center for National and Global Health Law, said, "The higher quality the mask, the better."

"If you're wearing an N95 respirator or KN95 that's well fitted, you're certainly much better protected than you would be if you are not wearing a mask," he said. And the more people wearing masks around you, the more protection there will be, he added.

However, even the best N95 won't protect against infection if people don't actually wear them.

The virus can spread over long distances, including in indoor spaces, such as restaurants and bars, where people are usually maskless and in close proximity to each other, said Dr. Isaac Bogoch, an infectious diseases physician and associate professor of medicine at the University of Toronto.

A CDC report published in March found that restaurants reopening during the first months of the pandemic in 2020 led to a growth rate in cases after more than a month.

"I know it sounds painfully obvious," Bogoch said. "You can have the best-quality masks. However, if you are removing it for prolonged periods of time in indoor spaces, for example, to eat lunch, then it's not going to provide significant protection."

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