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23 Jul 2021

New study finds that spit test just as effective as throat and nasal swabs for detecting COVID-19 in adults

Peer review: Medical Journal of Australia
Funding: University of Melbourne Emergency Response Appeal, Isabel and John Gilbertson Charitable Trust

A new study by researchers from the Peter Doherty Institute for Infection and Immunity (Doherty Institute) has shown that in adults, testing saliva is just as effective as testing throat and nose swabs when it comes to detecting SARS-CoV-2, the virus which causes COVID-19.

The study, published in the Medical Journal of Australia, includes over 1000 participants from three sites around Melbourne, Victoria.

Both throat and nose swabs, and saliva samples were taken from each participant and tested for COVID-19 when they visited a testing clinic.

Study Coordinator Dr Jane Oliver, a Postdoctoral Fellow at the Doherty Institute, said the swab results from each participant were then compared to their saliva test results.

“There were a few instances where participants would show a positive result from their swab and a negative result from the spit, or vice versa,” said Dr Oliver.

“But in general, the saliva tests were just as reliable.”

Unfortunately, for children, particularly those younger than 10 years old, a saliva sample was not sufficient to diagnose COVID-19. 

“Of the 19 children under 10 years old who tested positive for SARS-CoV-2, only two had both their swab and their saliva sample test positive,” explained Dr Oliver.  “Further research is needed to investigate saliva in this age group”, says Dr Oliver as more than 90% of parents stated they preferred saliva to swabs for children aged less than 10 years.

Overall, three-quarters of people in the study preferred giving saliva to having the swab. These findings support the continued use of saliva tests in settings where people must undergo frequent testing, such as for healthcare and hotel quarantine workers. 

“Saliva testing is far less invasive which greatly benefits those individuals who are required to be tested frequently for COVID-19, and might also be used in situations where people are very reluctant to have a swab,” said Dr Oliver. 

Saliva testing is not routinely available in most testing centres in Australia currently and requires specific laboratory and handling processes. 

This study was done in collaboration with the Murdoch Children's Research Institute, the Royal Children's Hospital, and The Royal Melbourne Hospital.