CDC Says Proper Double Masking Offers More Protection Against The Coronavirus

Maximizing Fit for Cloth and Medical Procedure Masks to Improve Performance and Reduce SARS-CoV-2 Transmission and Exposure, 2021

February 11, 2021

0 3 minutes read

The Centers for Disease Control and Prevention released new research on Wednesday that found wearing a mask over a surgical mask offers more protection against the coronavirus, as does tying knots on the ear loops of surgical masks. Those findings prompted new guidance on how to improve mask fit at a time of concern over fast-spreading variants of the virus. For optimal protection, the CDC says, wearing a tight-fitting surgical mask, or doubling up on masks, can significantly reduce COVID-19 transmission and slow the spread of new, more contagious strains.

Researchers found that if two people are both wearing surgical masks that are knotted and tucked flush to the face -or if both are wearing a cloth mask over a surgical mask– exposure to viral particles is cut by more than 95%.

“The data in this report underscore the finding that good fit can increase overall mask efficiency,” the authors wrote. “Multiple simple ways to improve fit have been demonstrated to be effective.”

A “simulated breathing experiment” shows surgical masks on their own block 42% of COVID-19 particles for the wearer, and cloth masks block about 44% of particles. Wearing a cloth mask over a surgical mask increased protection for the person wearing the masks, blocking 83% of small particles.While other recent studies looked at “mask fitters” a band that goes over a mask to keep it snug to the face and found they improved performance, the CDC said it believes the best fit comes from wearing a surgical mask covered by a cloth mask.

“In the study, wearing any type of mask performed significantly better than not wearing a mask,” said CDC Director Rochelle Walensky in a briefing from the White House COVID-19 Response Team on Wednesday.

“And well-fitting masks provided the greatest performance at both blocking emitted aerosols and exposure of aerosols to the receiver. In the breathing experiment, having both the source and the receiver wear masks modified to fit better reduced the receiver’s exposure by more than 95%, compared to no mask at all,” she said.

Double Masking Against Highly Contagious COVID-19 Variants

COVID deaths in the U.S. jumped in November and, though they are declining, are still high. Officials have warned that the U.K.-based variant could ultimately become the dominant strain in the U.S. by March.

These findings emerge among growing concerns about three new, highly contagious COVID-19 variants first identified in the U.K., South Africa, and Brazil. All three have all made their way across U.S. borders.

Regarding the new coronavirus variants, CDC Director Rochelle Walensky, MD, told reporters at a White House briefing Wednesday that the agency currently estimates that 1%-4% of COVID cases in the U.S. were caused by the U.K. variant, also known as B117.

On the mask study, Walensky said the science was already clear that mask requirements can decrease COVID-19 infections and deaths. But, she said, the new CDC research “underscores the importance of wearing a mask correctly and making sure it fits closely and snugly over the nose and mouth.”

Walensky said any type of mask offers some protection, “and well-fitting masks provided the greatest performance both in blocking emitted aerosols and exposure of aerosols to the receiver.”Though little was known about mask protection at the start of the pandemic, mounting research provides clear evidence that they work well. A June paper in the journal Physics of Fluids explained that a cough can cause droplets to travel 12 feet within about 50 seconds. With a properly fitting homemade cotton mask made up of multiple layers, those droplets only traveled about 2.5 inches.

CDC Says Proper Double Masking — Fitting the mask snugly against the sides of your face, and slipping the loops over your ears or tying the strings behind your head.

An April study in Nature Medicine found surgical masks drastically reduced transmission of both cold and flu droplets. A January paper in TheLancet Digital Health says an increase in mask-wearing in a community would more than triple its likelihood of controlling COVID-19 spread.

Finally, a CDC study released this month found that from March 22 to Oct. 17, 2020, 10 sites in states with mask mandates reported a decline in COVID-19 hospitalization growth rates by up to 5.5 percentage points. Currently, there are more than 40 states and territories with mask mandates.

To ensure proper mask-wearing, the CDC recommendations include:

Choosing a mask that has two or more layers of washable, breathable fabric
Putting the mask over your nose and mouth and securing it under your chin
Knotting the ear loops of a surgical mask, where they attach to the mask, and then tucking in and flattening the extra material close to the face (knotted and tucked masks)
Fitting the mask snugly against the sides of your face, and slipping the loops over your ears or tying the strings behind your head
If you have to continually adjust your mask, it doesn’t fit properly, and you might need to find a different mask type or brand.
Wearing your mask under your scarf, ski mask, or balaclavain cold weather
Keeping a spare mask to replace one that becomes wet
Storing wet reusable masks in a plastic bag until they can be washed