Early on in the COVID-19 pandemic, health experts said masks weren’t necessary.
“There’s no reason to be walking around with a mask,” Dr. Anthony Fauci, an immunologist and director of the National Institute of Allergy and Infectious Diseases who served on the White House Coronavirus Task Force, said in March on CBS News. “When you’re in the middle of an outbreak, wearing a mask might make people feel a little bit better and it might even block a droplet, but it’s not providing the perfect protection that people think that it is.”
But the response to the virus has been evolving ever since. Soon after Fauci made his comments, experts — including the Center for Disease Control and Prevention (CDC) — said Americans should wear masks, citing estimates that 40% or more of those infected were asymptomatic but could still spread the virus.
“We were not aware that 40% to 45% of people were asymptomatic, nor were we aware that a substantial proportion of people who get infected get infected from people who are without symptoms. That makes it overwhelmingly important for everyone to wear a mask,” Fauci said in September, noting that “the data now are very, very clear.”
While masks were deemed useful to protect others, the efficacy of masks for the wearer was in question.
Now, the CDC says mask wearers get a measurable amount of protection against the virus, saying masks “reduce inhalation” of possible virus-laden droplets.
“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,” the CDC reported on Tuesday. “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.”
“Adopting universal masking policies can help avert future lockdowns, especially if combined with other non-pharmaceutical interventions such as social distancing, hand hygiene, and adequate ventilation,” the CDC said. “The prevention benefit of masking is derived from the combination of source control and personal protection for the mask wearer.”
“The relationship between source control and personal protection is likely complementary and possibly synergistic, so that individual benefit increases with increasing community mask use,” according to the agency.
The CDC also reported results on various materials used in 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,” it said. Others such as silk “may help repel moist droplets and reduce fabric wetting and thus maintain breathability and comfort,” the agency added.
“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,” the CDC said.