By Jeremy Peplow - November 30, 2020
It’s what many had already assumed but the Centers for Disease Control and Prevention now wants to make it official: A mask protects the person who wears it.
Since the start of the COVID-19 pandemic, the CDC has been advising people to wear masks because of evidence that it stops people who are infected with coronavirus — whether they know it or not — from spreading it to others.
But this week the CDC posted a new scientific brief discussing recent studies that demonstrate a wearer gets some protection.
“Wearing a mask protects both the wearer and the people they encounter with clear evidence,” said Dr. John Greene, chair of the Infectious Diseases Department at Moffitt Cancer Center. “A mask prevents sick people from infecting others and it prevents the person wearing the mask from being infected.”
"Wearing a mask protects both the wearer and the people they encounter with clear evidence."- Dr. John Greene
CDC officials crafted guidance based on real-world observational and epidemiological studies from around the world.
An additional study from Japanese researchers led the CDC to confirm that masks block about 60% of the amount of virus emitted by an infected person, but the research also found there was a benefit when an uninfected person wearing a mask was unlucky enough to be near an infected person. In that scenario, the amount of virus the uninfected person inhaled fell by 37% to 50% if they wore a mask.
When both people were wearing masks, the decline in virus particles reaching the second person was largest — close to 70%.
“The CDC guidance confirms adopting universal masking policies can help avert future lockdowns, especially if combined with other interventions such as social distancing, hand hygiene, and adequate ventilation,” said Greene.