Switching New Zealand's required method of Covid-19 testing could be on the horizon as the roll-out of voluntary saliva tests widens.
Auckland Airport workers are now being offered saliva testing in a bid to add another layer of protection.
It comes after the Government last month rolled out the additional testing method for border workers in quarantine facilities.
While the Ministry of Health say at this stage there is still no indication that saliva PCR testing could replace the mandatory nasopharyngeal testing, health experts say it's only a matter of time.
Otago University epidemiologist Professor Michael Baker said once everyone was convinced the performance of saliva testing was adequate it could certainly replace nasal swab testing.
"It means we could contemplate the idea of having daily tests as a way of increasing the speed of outbreak protection," Baker said.
Baker said it was good New Zealand had multiple laboratories testing out these technologies as the benefits were huge.
"Saliva testing is a lot less invasive for people ... potentially switching to saliva testing, especially for workforce who are already feeling more vulnerable, could make the job that much easier."
Mary-Liz Tuck, Auckland Airport general manager of corporate services, said it made asymptomatic testing simple and comfortable for airport and border workers, while providing the highest standard of protection for the community.
"We want to see as many protective layers as possible for our people and our community," Tuck said.
The airport teamed up with New Zealand business Rako Science that established the Covid-19 surveillance testing in New Zealand using the Shield saliva test developed at the University of Illinois.
A collection site in Auckland Airport's international terminal had now been set up to provide the saliva testing and was set to run for three months while scientists measured the effectiveness.
Airport staff taking part in the saliva tests were doing so on a voluntary basis, along with the mandatory nasal-swab testing required by the Government's border policies.
A Ministry of Health spokeswoman said PCR nasopharyngeal swabbing method was still considered the gold standard for Covid testing as it detects the virus the most effectively.
"This swab type will obtain the optimal specimen and is the preferred collection method for both symptomatic and asymptomatic testing due to its higher sensitivity in detecting the virus."
She said voluntary saliva testing also recommenced this week at the Auckland quarantine facility and at the managed isolation and quarantine facility in Christchurch.
Rako Science is using the RT-qPCR saliva-testing protocol developed by University of Illinois which has conducted 1.3 million on-campus tests.
Rako Science's Chief Science officer, Dr Stephen Grice, said Rako's science committee had briefed the Ministry of Health in December last year that it had successfully validated and accredited the saliva test for New Zealand.
He said they recently provided the ministry with additional data which confirmed the test was as accurate as tests using nasal swabs.
"Rako Science has the processing capacity for 10,000 tests per day and the sample collection system does not depend on medical professionals to administer the test."
Saliva testing for Covid-19 had been accredited for use in New Zealand by International Accreditation New Zealand (IANZ).
Separately, Air New Zealand staff were working with the Institute of Environmental Science and Research (ESR) to work out the effectiveness of saliva tests detecting Covid-19.
The Rako Science saliva deployment had no connection to trials being run by ESR.
Last month, Covid-19 Response Minister Chris Hipkins said Covid-19 the role and effectiveness of saliva testing was still evolving.
"The Ministry of Health will report back with its findings about the testing in early March," he said at the time.