Covid-19: Saliva testing at the Level 4 Auckland boundary
Wednesday, 8 September 2021
Saliva testing is being expanded further than first promised, despite months of delay in getting it to border workers.
Director General of Health Ashley Bloomfield said the Ministry of Health was negotiating with an unnamed company to provide saliva testing to more people, especially essential workers passing through the Auckland level 4 boundary.
The ministry has a saliva testing contract with Asia Pacific Healthcare Group (APHG) for its border workers, but the company’s chief executive, Anoop Singh, said he was not sure what the plans were for polymerase chain reaction (PCR) saliva testing at the Auckland boundary.
“We are just waiting for the ministry to make up their minds as to what they want to do. I don’t know exactly what’s happening in this space because the ministry hasn’t formally advised us as to what they’d like to do.”
**READ MORE:
* Covid-19: The issues with saliva tests, and why NZ's rollout has been so slow
* Covid-19: Ministry of Health 'now confident' saliva testing could identify cases early
* Slow saliva testing roll-out hurting New Zealand's ability to get on top of outbreak: Scientist
**
The ministry says the details around how a saliva testing regime for workers at the Auckland boundary could work are still being finalised.
But it did say anyone crossing the boundary after 11.59pm on Thursday would need to present evidence they had taken a Covid-19 test once within the past seven days, and clarified these would have to be a nasopharyngeal test (nasal swab), or an oropharyngeal bilateral anterior nares test (throat swab).
On Tuesday, Bloomfield said the ministry was finalising a contract with an “additional provider” to APHG, to support a wider system of saliva testing for workers moving across the Auckland boundary, and to test employees at various Auckland businesses over the next few weeks.
Saliva testing involves a person drooling into a spoon then tipping that saliva into a small collection tube to drop off at a collection point. People need to abstain from eating or drinking anything for half an hour beforehand, and results can often be provided in a few hours. Tests can be self-collected then mailed in, or dropped off at collection sites for processing.
The tests can be collected without trained medical personnel, and it is not as invasive as a nasal swab, so people can be tested more frequently. The Ministry of Health has also acknowledged saliva test can be as accurate as a nasal swab.
Anne Wyllie, a Yale University scientist whose work on PCR saliva testing led US radio station NPR dub her “The Spit Queen”, said testing at the Auckland boundary would be a judgment call on how likely the workers were to come into contact with people infected with the virus.
For universities and schools looking to re-open overseas, Wyllie has often recommended testing saliva twice a week, and more frequent saliva testing for border workers.
But if the ministry thought essential workers moving across the Auckland boundary were unlikely to come into contact with people infected with Covid-19 then the cost of testing people twice a week might outweigh the benefits.
“Even schools doing once per week testing are still identifying cases early enough that they are able to then focus on their close contacts…put that ring around the outbreak, isolate those individuals, and stop further transmission, further outbreaks.”
She wants to get more PCR saliva testing providers into the market. This would provide more competition, and bring down the costs of saliva testing to the types of prices seen overseas. Saliva PCR testing is still less expensive than nasal swab testing, which costs the taxpayer $130 per test.
Saliva testing is still in its infancy here, despite widespread use internationally, largely thanks to a rocky roll-out saga between Rako Science, the Ministry of Health and APHG, with debates over testing accuracy being aired publicly and behind the scenes.
Singh says APHG’s test has been diagnostically validated like Rako’s, but he would not reveal details on percentage specificity or sensitivity of their test, or when this validation was achieved.
“The sensitivity of the saliva samples that we’ve gone through, have been compared with the nasopharyngeal, have a similar sensitivity [to nasal swabs]. That’s the advice that our pathologists are giving us, otherwise we won't do it.”
Pressure on the Government over the saliva testing issue ratcheted up a notch after the Delta variant took hold in New Zealand.
The testing and contact tracing systems struggled with the number of people who needed to be isolated and tested within those first few days of the outbreak.
Wyllie’s colleague at Yale, Steph Tan, said the debate about the accuracy of saliva testing had cost New Zealand valuable time in putting a saliva testing regime in place, and she was glad that something now seemed to be happening.
“People talk about the danger of using certain methods, or not using certain methods, and then they forget about the danger of doing nothing at all, which is actually what happened.”