Scientists studying the SARS-CoV-2 coronavirus — which causes COVID-19 — believe they’ve discovered why face masks might help limit transmission of the virus.
The virus tends to first infect the nasal cavity, replicating less well in the lower respiratory tract, University of North Carolina (UNC) researchers found. However, sometimes it’s sucked into the lungs, where it can cause serious consequences, including fatal pneumonia.
“If the nose is the dominant initial site from which lung infections are seeded, then the widespread use of masks to protect the nasal passages, as well as any therapeutic strategies that reduce virus in the nose, such as nasal irrigation or antiviral nasal sprays, could be beneficial,” study co-author Dr. Richard Boucher said in a university news release.
Boucher is a professor of medicine and director of the UNC School of Medicine’s Lung Institute.
The study reveals new information about disease progression and severity following infection, the researchers said.
In a series of lab experiments, the investigators found that the virus can easily infect cells in the nose, but less so the cells lining the throat and bronchia, and less still the lung cells.
The findings also showed that cells in the nasal passage had more of the ACE2 protein that the virus needs to attach itself than the lower respiratory system. This might explain why the nose is ground zero for the infection.
The researchers also found that some airway cells weren’t infected, which was intriguing, they noted.
That suggests that unknown factors in airway cells determine how the infection progresses and may explain why some people get sicker than others and why some people have no symptoms at all, the study authors added.
It’s also possible that people who have been exposed to other coronaviruses may have some immunity to SARS-CoV-2, the researchers said.
According to James Kiley, director of the division of lung diseases at the U.S. National Heart, Lung, and Blood Institute, “These results, using some novel and innovative methodology, open new directions for future studies on SARS-CoV-2 that may guide therapeutic development and practices for reducing transmission and severity of COVID-19.”
The report was published online May 26 in the journal Cell.
For more on COVID-19, see the U.S. Centers for Disease Control and Prevention.