Federal health officials on Wednesday urged Americans to keep their masks on and take steps to make them fit better – or even to cover a cloth over a surgical mask – and say new research has shown that masks spread the coronavirus significantly reduced.
Recent laboratory experiments have found that viral transmission can be reduced by 96.5 percent if Americans wear cozy surgical masks or a combination of cloth and surgical mask. Dr. Rochelle P. Walensky, director of the Centers for Disease Control and Prevention, told the Americans to wear a ‘well-fitting mask’.
“With cases, hospitalizations and deaths still very high, now is not the time to withdraw mask requirements,” she said. “The end result is: masks work, and they work if they fit well and are worn correctly.”
Masking is now mandatory for federal property and for domestic and international transportation. Studies conducted in households in Beijing, hair salons in Missouri and aboard an aircraft carrier in Guam have shown that ‘any mask is better than none’, said Dr. John T. Brooks, chief medical officer for Covid response at the CDC, said. author of the agency’s new research on masking.
“Wearing a mask reduces the spread, and in communities wearing a mask, new infections carry off,” said Dr. Brooks said.
However, while masks reduce the respiratory droplets and aerosols exhaled by infected carriers and protect uninfected carriers, air leaking to the sides of a mask may reduce their effectiveness. The agency’s new laboratory experiments have shown how the problem can be solved.
One agency is to wear a cloth mask over a surgical mask, the agency said. The alternative is to apply the surgical mask more tightly to the face by “knotting and tucking in” – that is, tying the two strands of the earlobes together, where it attaches to the edge of the mask, and then the fold up extra fabric and flatten the edge of the mask and insert it for a tighter seal.
The agency’s experiments relied on three-layer surgical and cloth masks, and only one type of each mask was tested. Other combinations, such as doubling a cloth mask or wearing two surgical masks, or applying a surgical mask over the cloth mask, have not been tested.
The advice comes even when states have begun lifting measures aimed at delaying the transmission of the virus. About three dozen states have masking requirements, but on Monday, Iowa ended its mandate and joined Mississippi and North Dakota, which it did months ago.
States rush to restart businesses and reopen schools. New York Governor Andrew Cuomo, for example, announced Wednesday that fans will be allowed to return to stadiums and arenas for sporting events and concerts, on limited capacity with mandatory tests and seating. New York City will soon be able to eat on Friday, with a capacity of 25 percent.
Virus-related deaths, which rose sharply in the United States in November and are still high, appear to be declining gradually. New cases and hospitalizations also began to decline last month.
But the CDC has warned that the new variant, even if the number of cases has decreased, will cause infections to skyrocket as Americans let their guards down. Cases of a more contagious virus variant first found in Britain double approximately 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 suppress it’, said dr. William Schaffner, a specialist in infectious diseases at Vanderbilt University, said. Masks are an effective, easy way to do this, and avoid another catastrophic ‘roller coaster’, he added.
“The fewer opportunities we give this virus to multiply, the less likely it is that mutations will occur and the less likely we are to get new variants,” said Dr. Schaffner said.
Dr. Monica Gandhi, a specialist in infectious diseases at the University of California, San Francisco, is the co-author of a paper to make masks more effective that inspired the CDC to conduct the new research.
“We want to do our best to bump up the transmission with all the elements: masking, distancing, hand hygiene, ventilation,” she said. “If we undermine the transmission and vaccinate en masse at the same time, the virus has no chance of evading the vaccine.”
The CDC has outlined some additional options to improve the effectiveness of masks, including the use of a mask-fitter – a frame that faces the face – over a mask. Recent studies have found that mechanics can increase protection against aerosols with viruses by 90 percent or more.
Surprisingly, perhaps, the agency also suggested that people consider wearing a sleeve of bare nylon stocking material around the neck and pulling it on top of a cloth or surgical mask.
The CDC’s recommendations are based in part on ideas put forward by Drs. Gandhi and Linsey Marr, an aerosol transfer expert at Virginia Tech. The two recommended a surgical mask covered with a sealing machine, or a three-layer cloth mask consisting of two outer layers of tightly woven material that embraces the face and a medium layer of filter material, such as dust from vacuum.
Both the tight fit and the filtration are important, said dr. Marr said. Even with an N95 respirator mask, the kind used by healthcare professionals, a good fit is essential.
While a growing number of Americans say they support wearing masks, there is resistance in some circles and in some regions. Dr Marr said she expected the CDC’s new advice to be ridiculed.
“I’m sure the opponents will say, ‘What’s next? Three masks? Four masks? ” The dr. Marr said. ‘But there is a lot of interest from people who want to know how good their masks are and how they can make them better. People want the best possible protection. ”
The CDC experiments mimicked the production of aerosols from a cough and estimated their absorption. While an unbuttoned surgical mask blocked 42 percent of the particles and a cloth mask alone blocked 44.3 percent, the combination of a cloth mask over a surgical mask blocked 92.5 percent of the coughed particles, dr. Brooks and his colleagues found.
When both the source of the aerosols and the exposed form were equipped with the combination of masks or the knotted surgical mask, the exposure to the recipient was reduced by 96.4 percent and 95.9 percent, respectively.
Neither method was perfect: to knot and to make the mask’s surface smaller, and may be more suitable for people with smaller faces, said dr. Brooks noted.
The combination of cloth and surgical mask also works well, but makes the mask thicker and can make it harder for some people to breathe. The additional layers can also obstruct the peripheral vision, increasing the risk of tripping or falling.
Breathing is also important, said dr. Marr said. “If you put too many things on top of each other that make it difficult to breathe, it’s counterproductive: it’s likely that air will find gaps to leak through,” she said.
Dr. Brooks emphasizes that masking, as Americans currently do, is not ‘inadequate’. But the new advice provides an opportunity to take it to the next level. ‘
“Now we are concerned about the forms of the virus that could transmit more effectively or undermine the usefulness of existing diagnostic, therapeutic and vaccines,” he added. “We need to improve our game to slow down the spread of the virus and slow down its evolution.”
Sheryl Gay Stolberg contributed reports from Washington.