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Federal health officials on Wednesday urged Americans to keep their masks on and take steps to make them more fitted – or even layering a fabric covering a surgical mask – saying new research had shown the masks significantly shrink the spread of the coronavirus.
Recent lab experiments have shown that viral transmission could be reduced by 96.5% if Americans wore tight-fitting surgical masks or a combination of fabric and surgical mask. In announcing the results, Dr. Rochelle P. Walensky, director of the Centers for Disease Control and Prevention, pleaded with Americans to wear a “tight-fitting mask.”
“With cases, hospitalizations and deaths still very high, now is not the time to roll back mask requirements,” she said. “The bottom line is this: Masks work, and they work when they are properly fitted and worn correctly.”
Masking is now mandatory on federal property and on national and international transport. Studies in households in Beijing, hair salons in Missouri and aboard an aircraft carrier in Guam have proven that “any mask is better than nothing,” said news writer Dr John T. agency research on masking.
“Wearing a mask reduces the spread, and in communities that adopt mask-wearing new infections are decreasing,” said Dr Brooks.
But while masks reduce respiratory droplets and aerosols exhaled by infected carriers and protect uninfected wearers, air leaking around the edges of a mask can reduce its effectiveness. The agency’s new lab experiments have shown how to fix the problem.
One option is to wear a cloth mask over a surgical mask, the agency said. The alternative is to adjust the surgical mask more tightly to the face by “tying and tucking” – that is, by tying the two strands of the earrings together where they attach to the edge of the mask, then by folding and flattening the extra fabric at the edge of the mask and tucking it in for a tighter seal.
The agency’s experiments were based on surgical and three-layer fabric masks, and only one type of each mask was tested. Other combinations – like lining up on fabric masks or wearing two surgical masks, or layering a surgical mask over a fabric mask – have not been tested.
The advice comes even as states have started lifting measures to slow the transmission of the virus. About three dozen states have masking requirements, but on Monday, Iowa ended its tenure, joining Mississippi and North Dakota, which it did months ago.
States are rushing to restart businesses and reopen schools. New York Governor Andrew Cuomo, for example, announced on Wednesday that supporters would be allowed to return to stadiums and arenas for sporting events and concerts, at limited capacity with mandatory testing and seating. New York City will allow dining in the dining room to resume on Friday, at a capacity of 25%.
Deaths linked to the virus, which resurfaced strongly in the United States in November and remain high, appear to be steadily declining. New cases and hospitalizations also started to decline last month.
But the CDC has warned that even as cases have declined, the new variants could explode infections if Americans let their guards down. Cases of a more contagious variant of the virus first discovered in Britain are doubling about every 10 days in the United States. The CDC warned last month that it could become the dominant variant in the country by March.
Until the vast majority of adults are vaccinated, “we want to fix that,” said Dr William Schaffner, an infectious disease specialist at Vanderbilt University. Masks are an effective and easy way to do this, avoiding another catastrophic “roller coaster”, he added.
“The less opportunity we give for this virus to multiply, the less chance there is for mutations to occur and the less likely we are to get new variants,” said Dr Schaffner.
Dr. Monica Gandhi, an infectious disease specialist at the University of California, San Francisco, is the co-author of an article on creating more effective masks that inspired the CDC to conduct the new research.
“We want to do our best to reduce transmission using all the elements: masking, keeping away, hand hygiene, ventilation,” she said. “If we reduce transmission and vaccinate en masse at the same time, there is no way the virus can escape the vaccine.”
The CDC presented a few more options to improve the effectiveness of masks, including the use of a mask-adjuster – a frame contoured to the face – over a mask. Recent studies have shown that fitters can increase protection against aerosols containing viruses by 90% or more.
Surprisingly, perhaps, the agency also suggested that people consider wearing a sheer nylon hosiery sleeve around the neck and pulling it up over a surgical fabric or mask.
The CDC’s recommendations were based in part on ideas formulated by Dr Gandhi and Linsey Marr, an aerosol transmission expert at Virginia Tech. Both recommended a surgical mask covered with a tight-fitting fabric mask or a three-layer fabric mask made up of two outer layers of tightly woven fabric that hug the face and a middle layer of filter material, like the material. of the vacuum bag.
The tight fit and filtration are both important, Dr Marr said. Even with an N95 respirator, the type used by healthcare workers, a good fit is essential.
While an increasing number of Americans say they support the wearing of masks, resistance persists in some circles and in some regions. Dr Marr said she expected the CDC’s new advice to be ridiculed.
“I’m sure the resistance will say, ‘What’s the next step? Three masks? Four masks? Dr Marr said. “But the people who want to know how good their masks are and how can they improve them is very interesting. People want the best possible protection. “
The CDC experiments simulated the production of aerosols from a cough and estimated their absorption. While an untied surgical mask blocked 42% of particles and a cloth-alone mask blocked 44.3%, the combination of a cloth mask over a surgical mask blocked 92.5% of cough particles, found Dr Brooks and colleagues.
When both the aerosol source and the exposed form were fitted with the combination of masks or the knotted and folded surgical mask, receptor exposure was reduced by 96.4% and 95.9%.
Neither method was perfect: tying and folding reduce the mask area and may be more appropriate for people with smaller faces, Dr Brooks noted.
Likewise, the combination of fabric and surgical mask works well, but makes the mask thicker and may make breathing more difficult for some people. The extra layers can also obstruct peripheral vision, increasing the risk of tripping or falling.
Breathability is also important, Dr Marr said. “If you layer too many things on top of each other that keep you from breathing, it’s counterproductive – it’s more likely that the air will find holes to infiltrate,” she says.
Dr Brooks stressed that masking, as Americans currently practice, is not “insufficient”. But the new advice offers “an opportunity to take it to the next level.”
“We are now concerned about forms of the virus that could be transmitted more efficiently or compromise the usefulness of existing diagnostics, therapies and vaccines,” he added. “We need to improve our game to slow the spread of the virus and slow its progress.”
Sheryl Gay Stolberg contributed reporting from Washington.
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