The oral cavity is an important site for COVID-19 infection, a recent study in Nature Medicine found. The study, “SARS-CoV-2 infection of the oral cavity and saliva” by Huang et al., was published in March 2021.
The article notes that “most attention [related to COVID-19] has focused on the nasal-lung axis of infection,” but the mouth plays a notable role in COVID-19 infection and symptoms. Many individuals report symptoms of taste loss, dry mouth and oral lesions. As has been widely reported, COVID-19 can be spread through speaking, breathing, coughing and singing — which is why face masks have become fixtures in society.
The researchers set out to better understand the “involvement of the oral cavity” in COVID-19.
To do so, the researchers first biopsied the salivary glands and gingival musca, then divided these tissues down to individual cells. Next, the authors generated schematics or “atlases” outlining the specific receptors in each of these unique cells. That allowed the researchers to confirm the expression of receptors (ACE2 and TMPRSS) — known entry sites for SARS-CoV-2.
What they found has implications for the growing understanding of COVID-19 and the continued global effort to reduce the transmission of the virus.
SARS-CoV-2 can infect cells in the mouth, meaning saliva from infected people — even asymptotic individuals – may be a route of virus transmission. The viral load in saliva is also correlated with symptoms, including loss of taste. The data show that the mouth is an important site for infection and opens the door to further research on SARS-CoV-2 transmission.
The study reinforces the importance of personal protective equipment (PPE) and face masks that cover both the nose and the mouth. It also shows the potential to test for COVID-19 using oral swabs in addition to nasal swabs, decreasing the false-negative rates of the tests.
For more details, read the article in Nature Medicine.