On Wednesday, federal health officials urged Americans to save their masks and take measures to tighten them – or even cover a cloth mask with a cloth – saying new research had shown masks to increase the spread of the coronavirus reduce.
Recent laboratory experiments found that virus transmission could be reduced by 96.5 percent if Americans wore tight-fitting surgical masks or a combination of cloth and surgical mask. When announcing the results, Dr. Rochelle P. Walensky, director of the Centers for Disease Control and Prevention, tells Americans to wear a “well-fitting mask.”
“With cases, hospitalizations and deaths still very high, now is not the time to reset mask requirements,” she said. “The bottom line is that masks work, and they work when they fit well and are worn properly.”
Masking is now mandatory on federal properties as well as on national and international transports. 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 of the CDC and lead author of the agency’s new research on masking.
“Wearing a mask reduces the spread and new infections are falling in communities where masks are used,” said Dr. Brooks.
While masks reduce the droplets and aerosols exhaled by infected wearers and protect uninfected wearers, air leaking from the edges of a mask can reduce its effectiveness. The agency’s new laboratory experiments showed how the problem can be fixed.
One option is to wear a cloth mask over a surgical mask, the agency said. The alternative is to “knot and tuck” the surgical mask closer to the face – that is, the two strands of the ear loops are knotted together where they are attached to the edge of the mask, and then the extra fabric is folded over and over flattened the mask edge and tuck it in 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 up on cloth masks or wearing two surgical masks, or putting one cloth mask on top of a surgical mask – were not tested.
The advice also arrives after states begin lifting measures to slow 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 are rushing to resume business and reopen schools. For example, New York Governor Andrew Cuomo announced on Wednesday that fans would be allowed to return to sporting events and concerts with limited capacity and mandatory testing and seating in stadiums and arenas. In New York City, indoor dining can resume on Friday at 25 percent capacity.
Virus-related deaths, which increased sharply in the US in November and remain high, appear to be steadily decreasing. New cases and hospital stays also fell last month.
But the CDC has warned that the new variants, even if cases have receded, could spike infections if Americans drop their guards. Cases of a contagious variant of the virus, first found in the UK, are doubling in the US about every 10 days. The CDC warned last month that it could become the dominant variant in the nation by March.
Until the vast majority of adults are vaccinated, “we want to contain this,” said Dr. William Schaffner, an infectious disease specialist at Vanderbilt University. Masks are an effective and easy way to avoid another disastrous “roller coaster ride,” he added.
Apr. 10, 2021, 6:02 p.m. ET
“The fewer opportunities we give this virus to reproduce, the less likely it is that mutations will occur and the less likely we are to get new variants,” said Dr. Conductor.
Dr. Monica Gandhi, an infectious disease specialist at the University of California at San Francisco, is the co-author of a paper on improving the effectiveness of masks that inspired the CDC to conduct the new research.
“We want to do our best to contain the transmission with all elements: masking, distancing, hand hygiene, ventilation,” she said. “If we reduce transmission and mass vaccinate at the same time, the virus has no way of evading the vaccine.”
The CDC outlined a few additional options for improving the effectiveness of masks, including using a mask fitter – a face-matched frame – over a mask. Recent studies have shown that fitters can increase protection against virus-containing aerosols by 90 percent or more.
Surprisingly, the agency may also suggest that people consider wearing a sleeve made of pure nylon stocking material around their necks and pulling it onto a drape or surgical mask.
The CDC’s recommendations were based in part on ideas from Dr. Gandhi and Linsey Marr, an aerosol transfer expert at Virginia Tech. They have also recommended a surgical mask covered with a tight-fitting cloth mask or a three-layer cloth mask made up of two outer layers of tightly woven cloth that wraps around the face and a middle layer of filter material, such as vacuum bag material.
Both the tight fit and filtration are important, said Dr. Marr. Even with an N95 respirator such as that used by health care workers, a good fit is essential.
While a growing number of Americans say they support the wearing of masks, opposition persists in some counties and regions. Dr. Marr said she expected the CDC’s new advice to be ridiculed.
“I’m sure the resistance fighters will say, ‘What’s next? Three masks? Four masks? Asked Dr. Marr. “But there’s a lot of interest from people who want to know how good their masks are and how they can improve them. People want the best possible protection. “
The CDC experiments simulated the production of aerosols from cough and estimated their absorption. While an untied surgical mask blocked 42 percent of the particles and a cloth mask alone blocked 44.3 percent, combining a cloth mask over a surgical mask blocked 92.5 percent of the cough particles, found Dr. Brooks and his colleagues.
When both the source of the aerosols and the exposed form were fitted with either the combination of masks or the knotted and hidden surgical mask, exposure to the recipient was reduced by 96.4 percent and 95.9 percent, respectively.
Neither method was perfect: knotting and tucking together makes the surface area of the mask smaller and potentially more suitable for people with smaller faces, noted Dr. Brooks.
Likewise, the fabric and surgical mask combination works well, but makes the mask thicker and can make it difficult for some people to breathe. The extra layers can also obstruct peripheral vision and increase the risk of tripping or falling.
Breathability is also important, said Dr. Marr. “If you put too many things on top of each other that make it difficult to breathe, it’s counterproductive: it’s more likely that air will find gaps to get in,” she said.
Dr. Brooks emphasized that masking, as Americans currently practice, is not “insufficient”. However, the new council offers “the opportunity to take it to the next level”.
“Now we are concerned about forms of the virus that could transmit more efficiently or interfere with the usefulness of existing diagnostics, therapeutics and vaccines,” he added. “We need to improve our game in order to spread the slowness of the virus and slow its development.”
Sheryl Gay Stolberg reported from Washington.