How infectious is the COVID-19 virus in saliva?

Swabs, Cotton, Swab, Clean, Ear, Ears, Hygiene

Bottom Line

Levels of the COVID-19 virus were consistently high in saliva, particularly in the early stages of the disease.


Yoon, J.G. et al. Clinical significance of a high SARS-Cov-2 viral load in the saliva. Journal of Korean Medical Science (2020).

Date Published:

25 May 2020


Patients can unknowingly spread the COVID-19 virus to others during the early stages of the disease (i.e. before the onset of symptoms). As such, it is important to understand how the virus is transmitted and which route leads to the highest rate of infection. In this preliminary study; saliva, urine, sputum, nose and mouth swab samples were collected from two patients diagnosed with COVID-19 every two days for one week. It was found that nasal swabs and saliva samples showed the greatest virus level during the early stages of the infection. Following one week, the virus was still detectable in the saliva of both patients while other samples showed a gradual reduction in virus levels. Interestingly, virus levels in the saliva decreased transiently for two hours after using chlorhexidine mouthwash, though levels slowly rose after 2-4 hours. In summary, virus levels were consistently high in saliva while chlorhexidine mouthwash was able to briefly reduce virus levels. This reinforces not only the importance of prevention practices but also highlighting the use of mouthwash as a possible controlling agent in droplet transmission.

Summary by: Edwin Wong