How Does Wearing a Mask Prevent Covid?

Here’s another reason to wear a mask in the midst of the COVID-19 pandemic.

New guidance from the Centers for Disease Control and Prevention (CDC) says face masks do in fact offer protection to the wearer in addition to helping to prevent the transmission of COVID-19.

Why does protecting your mouth matter?

Until now, scientists advised wearing facial coverings over the nose and mouth to prevent spreading the virus to others through airborne water droplets (saliva) released when talking, singing, yelling and sneezing.

The new CDC directive shows that exposure from infectious droplets is lowered through the filtration provided by masks. The protection levels increase with face masks that have multiple layers of fabrics and higher thread counts, according to the CDC.

While researchers say the nasal cavity, throat and lungs are primary infection points for the virus that causes COVID-19, a first-of-its kind study shows the mouth is a robust site for infection and transmission of COVID-19.

The study is published on the preprint server medRxiv. The results have not been peer reviewed, but it reinforces the importance of face coverings and social distancing.

Oral infection may play a role in asymptomatic spread

The researchers from UNC-Chapel Hill and the National Institute of Dental and Craniofacial Research discovered the coronavirus can take hold in the salivary glands and replicate. That can lead to prolonged disease when infected saliva is swallowed into the gastrointestinal tract or aspirated into the lungs where it can lead to pneumonia.

“Our results show oral infection of COVID-19 may be under appreciated,” Kevin Byrd, the senior study author and Research Instructor at the UNC Adams School of Dentistry told The Well, the research newsletter for UNC-Chapel Hill University Communications. “Like nasal infection, oral infection could underlie the asymptomatic spread that makes the disease so hard to contain.”

While many COVID-19 patients have indicated a loss of taste or smell as one of the symptoms of the disease, researchers are just beginning to look at the oral symptoms patients experience. Those symptoms also include persistent dry mouth.

The study focused on 40 patients with COVID-19. Researchers found sloughed epithelial cells lining the mouth can be infected with SARS-CoV-2, the coronavirus that causes COVID-19. The amount of virus in patient’s saliva was positively correlated with taste and smell changes, according to the study.

Scientists also surveyed tissues in the mouth with the highest levels of ACE2, the receptor that helps coronavirus grab and invade human cells. Those findings indicated the salivary glands, tongue and tonsil were the most likely infection points.

Combined with earlier research, the findings provide more evidence of the role of saliva in the COVID-19 pandemic. COVID-19 infection, specifically in the mouth, can allow the virus to spread internally and to others as the infected person breathes, speaks and coughs.