Rapid antigen testing will be one of New Zealand's key tools for combating the spread of the Omicron variant.
So how many tests do we have, when are we getting more and why do we need them?
Rapid antigen tests (RATs) are generally taken with a front of nose swab and detect the presence of specific proteins on the outer portion of the virus, such as the spike protein.
There are roughly 4.6 million test kits in the country, according to Prime Minister Jacinda Ardern today.
Yesterday, RNZ reported 10m more tests were confirmed to arrive in January and February, while delivery schedules during this time period for a further 21m were expected.
Another 20m tests for the March to June period were also on order.
After announcing the country would shift to the Red traffic light setting tonight, Ardern said rapid antigen testing would be incorporated into a new three-phase Omicron plan to be detailed on Wednesday.
She defended New Zealand's RATs stock, expressing confidence in the delivery schedule.
In a press conference this afternoon, National Party leader Chris Luxon strongly criticised what he saw as insufficient planning for Omicron from Ardern's Government.
On RATs, Luxon condemned the country's stock, pointing out there were more New Zealanders than there were tests.
"I can go to any supermarket in many other countries in the world, and [RATs] are freely available."
He said people had been talking about RATs for nine months or more, but no real progress had been made on distributing the kits.
"We need tens of millions of kits.
"We need to scramble, we need to secure those tests and get them here as quickly as possible."
Ardern and other health experts had formerly warned against relying too heavily on rapid antigen testing, as they were not as accurate as the more common PCR swab test.
However, many experts - like University of Melbourne epidemiologist Professor Tony Blakely - have emphasised their value in surveillance of large populations.
RAT shortages hit Australia hard as demand spiked alongside significant spread of the highly transmissible variant, leading experts to believe the country's Covid case tally was below the true count.
In New Zealand, rapid antigen testing was supposed to be accessible to the general public at pharmacies by mid-December, as announced by Minister Ayesha Verrall in November.
However, this was later changed in light of Auckland's border being relaxed, with unvaccinated travellers - who needed proof of a negative Covid test to exit Auckland - were encouraged to use RATs instead of PCR swab tests.
The Ministry of Health says the public would be able to buy RATs in the first quarter of 2022. Since late last year, some businesses had been purchasing rapid antigen testing for their staff.
In yesterday's RNZ story, South Auckland GP Dr Api Talemaitoga criticised the Government's rapid antigen testing plan as he waited on his order of 300 tests, ahead of requesting another 500.
"I have to be honest - someone has dropped the ball. We knew this was going to happen. We follow what happens overseas all the time, but there's not enough in the country. I keep on hearing there's thousands arriving but I don't know where they're storing them, they're not getting to frontline practice," Talemaitoga said.