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CDC Says Wearing Two Masks Offers Even More Protection

CDC Says Wearing Two Masks Offers Even More Protection

Double masking and ensuring a snug fit dramatically reduces exposure to potentially infectious particles, research shows.

Updated on February 10, 2021 at 2:00pm EST.

Wearing two masks is even better than one, reducing exposure to microscopic particles that could spread COVID-19 by up to 96 percent, according to new research from the Centers for Disease Control and Prevention (CDC).

This guidance comes as new, more contagious strains of the coronavirus complicate the massive COVID-19 vaccine rollout across the United States.

Recent experiments conducted by the CDC found that double-masking, or wearing a cloth mask on top of a medical procedure mask, blocked 92.5 percent of potentially infectious particles.

The CDC also determined, however, that the fit of medical masks could be improved in two ways to reduce exposure and prevent the spread of the coronavirus:

  1. Knotting the ear loops of a medical mask together where they attach to the mask
  2. Tucking and flattening the extra mask material so that it fits snuggly to the face

The CDC noted that if both the source of infectious particles and a possible receiver either double masked or utilized the knotting and tucking procedure, exposure to the coronavirus is reduced by 96 percent.

These experiments are supported by researcher commentary published in Cell Press on January 15, which suggests that wearing a surgical mask underneath a cloth mask provides even more protection. The idea is that the surgical mask serves as a filter while the cloth ensures a tight fit and an additional layer of protection against contaminated droplets or airborne particles.

Speaking to NBC News’ TODAY on January 25, Anthony Fauci, MD, White House advisor and director of the National Institute of Allergy and Infectious Diseases pointed out that the possible benefits of doubling up on masks is a no-brainer.

“If you have a physical covering with one layer, you put another layer on, it just makes common sense that it likely would be more effective,” Dr. Fauci said.

Why masks are even more important
Wearing a medical mask or cloth covering over your nose, mouth and chin doesn’t just protect the people around you from possible exposure to COVID-19. It helps protect you from the infection as well, according to the Centers for Disease Control and Prevention (CDC).

This message is particularly important as new strains of the coronavirus have been identified, including one new, highly contagious strain, called B117. As of January 25, 193 cases were detected in nearly two dozen states, the CDC reports.

Health officials warn that this strain could lead to a surge in new cases that require hospitalization and deaths over the coming months. The CDC is urging all Americans to remain vigilant and take all steps necessary to prevent the spread of the virus as the vaccine rollout continues, including social distancing, avoiding crowded indoor spaces with poor ventilation and diligent hand hygiene.

It’s also essential to continue to wear an effective mask or cloth face covering consistently—and properly—when in public or around other people to help stop the spread of COVID-19 as the vaccine rollout continues.

Recovery from the coronavirus isn’t a guarantee of long-term immunity. We still do not know exactly what kind of immunity a person has after recovering from COVID-19 or how long it will last. And if recovered people are immune (temporarily), it’s unclear if they could still spread the infection.

Even those who are vaccinated must continue to wear a mask. It’s still unclear if the vaccines block transmission or prevent someone from carrying the virus and silently spreading it to others.

Bottom line: Until the majority of the population is immune, even those who have recovered from COVID-19 or received the vaccine must continue to follow all precautions to prevent spreading the coronavirus to anyone else.

How effective are masks, really?
Masks aren’t foolproof and wearing one doesn't guarantee you protection against COVID-19—or any other serious upper respiratory infection, like the flu or measles.

But masks are needed to reduce the emission of contaminated respiratory droplets from infected people when they cough, sneeze, talk, sing or breathe. The CDC adds that wearing a mask also helps prevent people who are not infected from breathing in the contaminated droplets of others who are sick.

“The community benefit of masking for SARS-CoV-2 control is due to the combination of these effects,” the CDC states, noting that the benefits of masks increase as the number of people wearing them consistently and correctly also rises.

How mask help reduce exposure
There are a few routes that SARS-CoV-2 uses to invade the body: Contact, droplet and airborne transmission.

Contact transmission takes place when a person touches a contaminated surface and then touches their mouth, nose or eyes.

For droplet transmission, contaminated droplets escape the body of a sick person when they cough or sneeze, then land in a nearby person’s mouth or nose. These tiny droplets can travel about six feet from the person before gravity causes them to fall and settle.

During airborne transmission, tiny contaminated particles escape the body and can waft and linger in the air across even longer distances.

Cloth masks with multiple layers can block between 50 and 70 percent of contaminated particles, the CDC reports. They can also limit the forward spread or emission of the particles they fail to block.

Preventing silent spread of the coronavirus
Over the past year, mounting evidence has shown that people without any symptoms at all can spread the virus unknowingly.

These so-called “silent spreaders” have made the pandemic much more difficult to control since earlier containment strategies focused on the early detection and isolation of people who developed symptoms, such as fever, fatigue, coughing and shortness of breath.

In fact, the CDC points out that infected people with no symptoms are estimated to account for more than 50 percent of COVID-19 spread.

Essentially, everyone should assume that they may be a carrier of SARS-CoV-2.

Some masks are more effective
Some fabrics may offer more protection than others, the CDC explains. For example, polypropylene masks may be particularly effective since they may generate a form of static electricity that helps capture certain particles. Silk also stays drier than other fabrics and may be more effective in repelling wet droplets.

When choosing homemade mask material, find a fabric that is as dense as possible that will still allow you to breathe. In tests, the New York Times reported that HEPA furnace filters, vacuum cleaner bags, layers of 600-count pillowcases, quilted fabric and material similar to flannel pajamas performed well. Stacked coffee filters were also somewhat effective in capturing viral particles while scarves and bandanna material had lower scores.

Remember, air filters could shed small fibers that would be risky to inhale. So, if you use one, sandwich it between two layers of cotton fabric.

The “right way” to use a facemask
Surgical masks can gradually become soggy, absorbing water from the humid air and a person’s breath, rendering them ineffective. Meanwhile, masks that do come into contact with contaminated droplets could still spread an infection if someone touches the mask and transfers the virus to their fingers.

Using a face mask could actually increase the risk for infection among those who don’t use them properly. People who wear masks, for example, may tend to touch their face more often—with contaminated hands.

Before going out with a mask, take the following steps:

  • First, wash or sanitize your hands.
  • Put the mask on, with the absorbent side facing your skin. (This side is usually white, with the colored side out.)
  • Minimize gaps between its edges and your skin. Mold the stiff edge so it follows the contours of your nose.
  • While you’re wearing the mask, try not to touch it. If you do, wash your hands afterward.
  • Replace masks after they’ve become damp. If they’re intended for single use, discard them.
  • To take off the mask, remove it from behind—don’t touch the front, which may contain virus. Then throw it into an enclosed trash can. Avoid touching your eyes, nose, and mouth when taking it off.
  • Finally, wash your hands immediately after removing the mask.

Anyone who uses a cloth mask should be sure it's clean and wash their hands well with soap and water before putting it on and after taking it off.

Other safety precautions to take:

  • If the mask has ties, secure the bottom ones first with a bow behind your neck. Then, pull it up over your nose and mouth and secure the upper tied around your head.
  • Wash your hand every time you touch the mask while you are wearing it.
  • Once you take the mask off, assume it's contaminated on both sides. If it's not disposable, isolate it in a secure place until it can be washed.

Nondisposable masks should be washed in hot water after use. The CDC provides these guidelines on how to sanitize clothing, towels, linens and other laundry items:

  • Wash fabrics according to the manufacturer’s instructions, using the warmest water setting possible.
  • Be sure to dry the item completely.
  • Wear disposable gloves when handling dirty laundry, particularly from someone who is sick.

What about N95s?
Some people may also have heard about N95 masks, also called disposable N95 respirators. Early on in the pandemic, these masks were in short supply and reserved for frontline healthcare workers.

“These higher-quality face masks used in healthcare settings provide a face seal that allows only filtered air to reach the person,” explains Werner Bischoff, MD, PhD, professor of infectious diseases at the Wake Forest School of Medicine in Winston-Salem, North Carolina. “This provides a high degree of protection against airborne pathogens.”

With their ability to block 95 percent of airborne particles, N95s can reduce the risk for the transmission of germs via both the droplet and airborne routes—if they fit correctly.

These masks need to form a tight seal around their edges, fitting so closely that when wearers inhale, they feel the mask pull inward slightly. A person with a small face who wears a large mask will not be able to form that tight seal and the mask won’t offer enough protection. Even when properly fitted, N95s are uncomfortable, and they’re not appropriate for some people with respiratory difficulties.

Other precautions are still necessary
Masks can offer a false sense of security, leading people to, say, skip handwashing. But masks don’t eliminate the need for other prevention measures, such as:

  • Practice social distancing. That means stay at least 6 feet apart from other people.
  • Avoid crowded places, close-contact settings, and confined and enclosed spaces with poor ventilation.
  • Do not linger indoors around other people. The rule of thumb for exposure to SARS-CoV-2 is close contact with an infected person for a total of 15 minutes in a 24-hour period.
  • When indoors, increase circulation of outdoor air as much as possible. This includes opening windows, doors and turning on fans and keeping the air moving when you’re inside.
  • Avoid buildings with poor ventilation.
  • Wash your hands well and often with soap and water for at least 20 seconds.
  • Use an alcohol-based hand sanitizer that contains at least 60 percent alcohol (if soap and water aren’t available).
  • Avoid touching your face with unwashed hands.
  • Stay home from work or school if you are sick or have symptoms.
  • Cover coughs and sneezes with tissues that you then put in the trash.
  • Frequently disinfect surfaces with cleaning spray or wipes.

Medically reviewed in January 2021.

Sources:
Centers for Disease Control and Prevention. Maximizing Fit for Cloth and Medical Procedure Masks to Improve Performance and Reduce SARS-CoV-2 Transmission and Exposure, 2021. Feb 10, 2021.
CNBC. “Dr. Fauci: Double-masking makes ‘common sense’ and is likely more effective.” Jan 25, 2021.
Centers for Disease Control and Prevention. “US COVID-19 Cases Caused by Variants. Jan 25, 2021.
Monica Gandhi and Linsey C. Marr. Uniting Infectious Disease and Physical Science Principles on the Importance of Face Masks for COVID-19. Cell Press. Jan 15, 2021.
Centers for Disease Control and Prevention. “Emergence of SARS-CoV-2 B.1.1.7 Lineage — United States, December 29, 2020–January 12, 2021.” Jan 22, 2021.
Centers for Disease Control and Prevention. “Scientific Brief: Community Use of Cloth Masks to Control the Spread of SARS-CoV-2.” Nov 10, 2020.
Centers for Disease Control and Prevention. “How to Wear Masks.” Sept 3, 2020.
Centers for Disease Control and Prevention. “Coronavirus Disease 2019 (COVID-19): Appendices.” Oct 21, 2020.
World Health Organization. “Advice on the use of masks in the community, during home care and in health care settings in the context of the novel coronavirus (2019-nCoV) outbreak.”
World Health Organization. “Q&A on coronaviruses.”
Centers for Disease Control and Prevention. “2019-nCoV: What the Public Should Do.”
Centers for Disease Control and Prevention. “How Infections Spread.”
Centers for Disease Control and Prevention. “How 2019-nCoV Spreads.”
Centers for Disease Control and Prevention. “NIOSH-Approved N95 Particulate Filtering Facepiece Respirators.”
Centers for Disease Control and Prevention. “Interim Infection Prevention and Control Recommendations for Patients with Confirmed 2019 Novel Coronavirus (2019-nCoV) or Persons Under Investigation for 2019-nCoV in Healthcare Settings.”
San Francisco Department of Public Health. “How to Put on and Remove a Face Mask.”
Centers for Disease Control and Prevention. “2019 Novel Coronavirus: Prevention & Treatment.”
World Health Organization. "WHO Director-General's opening remarks at the media briefing on COVID-19 - 3 March 2020."

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