The Centers for Disease Control and Prevention has recommended the public wear masks primarily to stop the spread of COVID-19 from an infected person to a healthy person.

In their latest guidance updated Tuesday, Nov. 10, the CDC is saying masks can also keep people from contracting the virus from an infected person.

In a Scientific Brief the CDC is saying:

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.

How well a mask protects you has varied greatly depending on the design of the mask and the size of the particles the mask is filtering out. The CDC is saying "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."

Additionally the CDC has cited a series of studies that show the wearing of face masks does reduce the transmission of COVID-19.

At the top of the list are the two COVID-19 positive stylists who cut 139 clients hair at a Springfield, Missouri Great Clips in May. An investigation into the event found none of the 67 clients who consented to an interview and testing developed COVID-19. Both the clients and the stylists were wearing masks in the salon as directed by Great Clips corporate policy and local ordinance at the time.

Then there was the outbreak on the USS Theodore Roosevelt. An environment the CDC notes that does not offer the crew of the aircraft carrier much opportunity to social distance because of close quarters.  The CDC found the use of face coverings on board reduced the risk of getting the coronavirus by 70%.

And finally, investigations involving COVID-19 infected passengers on plane flights ten hours or longer suggests that in-flight transmission of the coronavirus are prevented by wearing masks. There is a notable absence of COVID-19 spread among passengers and crew on these flights in the fourteen days following exposure.

The CDC concludes, "Adopting universal masking policies can help avert future lock-downs, especially if combined with other non-pharmaceutical interventions such as social distancing, hand hygiene, and adequate ventilation."