Coronavirus can infect mouth tissues, spreading infection

The new coronavirus can infect salivary glands, which can then play a role in transmitting the virus to the lungs or digestive tract via saliva, according to a report published on Thursday in Nature Medicine. 

Researchers first studied mouth cells from healthy volunteers, looking for two proteins the coronavirus uses as entryways.

Cells in the salivary glands and the gums expressed both proteins, making them vulnerable to infection.

Next, researchers discovered genetic material from the virus in mouth tissues from COVID-19 patients, indicating infection.

They also found evidence that the virus was replicating in some of these cells.

Among 27 volunteers with mild COVID-19, those with virus in their saliva were more likely to report loss of taste and smell, suggesting that infected salivary glands might help explain some oral symptoms of COVID-19, the researchers said.

"The study's findings suggest that the mouth, via infected oral cells, plays a bigger role in SARS-CoV-2 infection than previously thought," study coauthor Kevin Byrd of the University of North Carolina at Chapel Hill said in a statement.

"When infected saliva is swallowed or tiny particles of it are inhaled, we think it can potentially transmit SARS-CoV-2" further into the body." -- Reuters