Mounting alarm over the emergence of more transmissible and perhaps deadlier mutations of COVID-19 is fueling calls for people to "double mask."
Notable among Americans double-masking are President Joe Biden and vice president Kamala Harris.
Wearing a surgical mask underneath a cloth mask will afford the wearer "over 91% removal efficiency for particles," according to Dr. Joseph Allen, an associate professor at the Harvard T.H. Chan School of Public Health and director of the school's Healthy Buildings program.
Using two masks creates "an obstacle course for the viral particle to make its way from the air into your nose and throat and then into your lungs," Dr. Dave Hnida, medical editor for CBS4 in Denver, said.
More contagious COVID-10 mutations first detected in the U.K., South Africa and Brazil have led doctors to suggest the quick fix but effective solution of double masking.
The mutation first detected in the UK in September is thought to be 70% more transmissible and might be 30% deadlier than the dominant strain.
The South African variant can evade antibodies generated by some COVID-19 treatments. The efficacy of current vaccines may be reduced.
U.S. public health officials now suggest double-masking as a way to increase the level of protection against COVID-19. "If you have a physical covering with one layer, you put another layer on, it just makes common sense that it's likely more effective - and that's the reason why you see people either double masking," Dr. Anthony Fauci, chief medical adviser to Biden, said.
A 2020 study found surgical masks are 50% effective at protecting the wearer from aerosols.
Also called medical-grade masks, surgical masks are made of three layers of nonwoven fabric typically made from plastic.
For maximum protection people can "wear a cloth mask tightly on top of a surgical mask where the surgical mask acts as a filter and the cloth mask provides an additional layer of filtration while improving the fit."
