Infectious disease expert Raina MacIntyre said while the saliva test could play a role in testing, it should be treated as a “back-up” and people must be counselled against relying on the result.
“If there’s any likely risk you’ve been exposed, you should take all the precautions and have a repeat test,” said Professor MacIntyre, who is head of the biosecurity research program at the University of NSW’s Kirby Institute.
She said there was also a risk of false negatives with throat-only swabs, with the nasopharyngeal test – where a 15cm swab is inserted into the cavity between the nose and mouth – the most reliable.
Victorian Health Minister Jenny Mikakos said the saliva test would initially be “concentrated in our priority suburbs”, where health authorities have launched a door-knocking blitz to test as many residents as possible.
“[The saliva test] will also be used in returned travellers in hotel quarantine, in particular to ensure that children in quarantine also have the opportunity to be tested,” Ms Mikakos said.
“Doing the traditional swab testing can be very uncomfortable for children as well as people with dementia and [in] nursing homes, people with disabilities and others.”
Victorian Premier Daniel Andrews on Sunday said one of the reasons for the high refusal rate for nose and throat swab tests in Victoria’s quarantine hotels was parents withholding consent for their small children.
Professor Lewin said it was far better to have a saliva test than no test at all and the institute would work with the Victorian Health Department to evaluate its efficacy over the longer term.
“The advantage of the saliva test is that it is much more acceptable for people to give a specimen, people just need to collect saliva in their mouth for a minute or two and then spit it into a small jar,” she said.
“We think it will play a role in bolstering testing reach across the state, particularly … in vulnerable populations or in people who have trouble with the throat swab such as children or other individuals who find it more acceptable.”
A federal Health Department spokeswoman said while the saliva test was not intended to replace the throat and nasal swab, it would help bolster the rate of testing across the community as it was “minimally invasive” and reduced the need for personal protective equipment for the tester.
NSW Chief Health Officer Dr Kerry Chant told the state Parliament’s public accountability committee hearing on Monday her department would monitor global and local research and evidence of “the reliability and feasibility” of the saliva tests before using them.
The Victorian government has followed NSW’s lead by adding 10 days to the hotel quarantine stay of returned travellers who refuse a COVID-19 test, after it emerged that up to 30 per cent were being released into the community without being tested. Fewer than 2 per cent of people quarantined in Sydney hotels have refused a test.
Doherty Institute researchers arrived at the 87 per cent accuracy figure by testing 600 people who presented with COVID-19 symptoms at the Royal Melbourne Hospital using both saliva and conventional throat and nasal swab tests.
The first 100 saliva tests were performed in Keilor Downs, the centre of one of Melbourne’s outbreaks, on Sunday.
With Kate Aubusson, Rachael Dexter and Michael Fowler
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Dana is health and industrial relations reporter for The Sydney Morning Herald and The Age.