Pre-departure COVID-19 tests aren't currently being considered for travellers to New Zealand because "the [managed isolation and quarantine] system is working here", Dr Ashley Bloomfield says.
The Director-General of Health said while these tests may add some value, such as infectious people being unable to fly, it won't change what is done once people arrive here.
His comments follow 23 new imported cases being announced on Wednesday, 18 of which are fishermen who arrived from Russia and the Ukraine on Friday. Everyone in this crew returned a negative pre-departure test before travelling on their chartered flight to New Zealand.
"What we've got here is a really good opportunity to look at the value that pre-departure testing adds or not," Dr Bloomfield told reporters on Wednesday.
"Now often [a pre-departure test] has to happen a few days before departure, especially if it's a PCR test, to get a result before they embark. And now what we've got is clearly a number of positive results here at day three that were negative on pre-departure testing."
He said this suggests pre-departure tests "may add some value" but it won't change New Zealand's COVID-19 protocols.
"The regime we have with our 14 days in managed isolation plus our day three and day 12 testing continues to be the mainstay of how we will keep the virus out of New Zealand," he said.
"At this point in time, the system is working here and whilst there may be the expectation of pre-departure testing, it won't change anything we will do at this end, which will be following absolutely rigid infection prevention controls and the testing."
A challenge of pre-departure testing is New Zealand authorities can't assess the validity of the test, including the process, the swabbing, how it's handled in a laboratory or any rapid testing process, Dr Bloomfield said.
Director of Public Health Caroline McElnay said the tests the fishermen took before arriving in New Zealand is being followed up, but it currently appears they had a PCR test.
"The real value of the pre-departure testing is when they test positive, because obviously, and that's what's happened in this situation, those individuals were then not allowed to board the plane and come to New Zealand," she said.
"But for the negatives, we just do not have access to that information to say, really, what is the accuracy of that test in another country."
Whether pre-departure tests should be a requirement for incoming travellers was contentious during the election campaign.
National said it would've made it compulsory for returnees to provide evidence of a negative COVID-19 test three days before their departure. They would then be required to have a test on days three and 12 in New Zealand, as is currently the case.
Health Minister Chris Hipkins described this policy idea as "fraught".
"One of the things that makes that fraught is that we've seen instances of people being infected in transit. So if you take someone leaving London, for example, they may go through several airports and it may take them a process of two or three days to get home, in which case they can become infected during that time," he said.