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Voluntary saliva tests for quarantine workers – Expert reaction

Workers in managed isolation facilities will have the option of having their spit tested for COVID-19 on a daily basis, in addition to the required weekly nasal swab tests.

The Government said today that the move was precautionary measure in response to higher rates of infection overseas and the more transmissible variants of COVID-19. This additional option will be rolled out at the Jet Park Quarantine facility in Auckland starting next Monday the 25th, and then to other dual-use Managed Isolation and Quarantine (MIQ) facilities in Wellington and Christchurch.

The SMC asked experts to comment on this announcement.

Professor Michael Plank, Te Pūnaha Matatini and University of Canterbury, comments:

“It’s good to see the government looking at bringing in saliva tests in addition to the standard nasopharyngeal swab tests for people working at the border.

“It’s likely these new tests are not as sensitive, meaning they will miss some cases, particularly in the early stages of infection. A negative test result isn’t a guarantee that you don’t have COVID-19. So it’s important that the new tests are an addition to existing test requirements, not a replacement.

“But, the advantage of saliva tests is they are easier and less invasive, which means they can potentially be done more often. Modelling shows that introducing regular saliva tests for quarantine workers, in addition to a weekly nasopharyngeal swab, means that cases are more likely to be detected before they can pass the virus on. This will reduce the risk of a community outbreak.”

Conflict of interest statement: I am partly funded by MBIE for research on mathematical modelling of COVID-19.

Lesley Gray, Senior Lecturer, Department of Primary Health Care & General Practice, University of Otago, comments:

“I think it is a great development to have saliva tests as an option as there is no doubt the invasive nasal swab can be uncomfortable, especially for workers who have to undergo regular testing. I am following the emerging research on the utility of saliva testing. There are encouraging signs from initial research overseas that suggest saliva might be a good predictor of COVID-19 severity in those with the infection and one study just published in the leading medical journal JAMA Internal Medicine found that testing for COVID-19 in saliva samples was nearly as sensitive as the nasal swabs.

“Down the line, potentially there might be a quick near person test using saliva that could help those needing to travel on flights (returning citizens and residents) and potentially could lead to shorter quarantine times if tests are ‘sensitive’ (accurate) enough. Although currently we know that it can take a few days for someone infected to produce a positive test and some people even when positive for COVID-19 might still give a negative test result, so it is not 100% accurate.”

No conflict of interest.