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."

- 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.