This is pretty important news. During the COVID-19 pandemic mask-wearing has been (rightly) characterized as an effective and proven means of protecting others from the spread of the virus. However, the data initially suggested that while potentially helpful, masks were not particularly effective in protecting oneself from infection. This always seemed a bit counterintuitive but that was, in fact, what the data suggested.
As reported by the New York Times, the CDC has now amended its guidelines to reflect the fact that masks are unequivocally beneficial in protecting yourself from infection.
Breaking from its tentative recommendations on mask use thus far, the Centers for Disease Control and Prevention said on Tuesday that using masks benefits wearers, which is a step beyond its previous declaration that said wearing masks would only protect those around them.
“Experimental and epidemiological data support community masking to reduce the spread” of the virus, the C.D.C. said in a document that details scientific evidence supporting mask use. “Individual benefit increases with increasing community mask use,” it said.
The unequivocal statements are a departure from the agency’s previous language, which suggested that “the latest science may convince” Americans to wear masks and that mask use could prevent an infected person from spreading the virus to others. “The main protection individuals gain from masking occurs when others in their communities also wear face coverings,” it said.
From the Scientific Brief: Community Use of Cloth Masks to Control the Spread of SARS-CoV-2:
Masks are primarily intended to reduce the emission of virus-laden droplets (“source control”), which is especially relevant for asymptomatic or presymptomatic infected wearers who feel well and may be unaware of their infectiousness to others, and who are estimated to account for more than 50% of transmissions.1,2 Masks also help reduce inhalation of these droplets by the wearer (“filtration for personal protection”). The community benefit of masking for SARS-CoV-2 control is due to the combination of these effects; individual prevention benefit increases with increasing numbers of people using masks consistently and correctly.
(emphasis supplied)
The CDC brief specifically addresses cloth masks.
Studies demonstrate that cloth mask materials can also reduce wearers’ exposure to infectious droplets through filtration, including filtration of fine droplets and particles less than 10 microns. The relative filtration effectiveness of various masks has varied widely across studies, in large part due to variation in experimental design and particle sizes analyzed. Multiple layers of cloth with higher thread counts have demonstrated superior performance compared to single layers of cloth with lower thread counts, in some cases filtering nearly 50% of fine particles less than 1 micron.
NIAID Director Anthony Fauci explains the significance here, as reported by CNN:
"It's a two-way street," Dr. Anthony Fauci, National Institute of Allergy and Infectious Diseases director, said Tuesday on MSNBC. "You protect others, their mask protects you, and your mask also protects you."
From a practical standpoint, the CDC’s revised guidance eliminates any possible argument for not wearing masks when needed. Even if you don’t care about protecting others, you will be protecting yourself.