A single case on August 17 put the whole nation into lockdown - which was the right thing to do as at that stage there were hundreds of undetected cases throughout Auckland and some in Wellington.
Now the question is how Prime Minister Jacinda Ardern and director-general of health Ashley Bloomfield will respond with two new cases in the Waikato, which were announced this morning by the Ministry of Health.
It will almost certainly require a response to move Waikato into at least level 3, if the Government is sincere - as it should be - about continuing to pursue elimination while vaccination rates remain relatively low.
Most cases are actually Covid duds, meaning they don't infect anyone else, and New Zealand has benefitted from this - such as the Delta case from Sydney in Wellington who didn't infect anyone despite a busy weekend schedule.
But that is not the case here.
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One case, in Raglan, has already infected a person who lives in Hamilton East and is being treated in Waikato Hospital for Covid symptoms.
This happened during the five days that the Raglan case was infectious before feeling unwell, getting tested and isolating.
Waikato has been at level 2. Vaccination levels sit below the national average - at just over 40 per cent fully vaccinated, and under 75 per cent for one dose.
There are no restrictions on household bubbles at level 2. People don't wear masks in cafes, bars and restaurants because they have to eat and drink. Gatherings of up to 100 people are permitted.
And five days is long enough for two cycles - where the case infects someone who then infects someone else.
"It's really hard to predict in individual cases, but yes, some people appear to be infectious within a couple of days, and you can go through several cycles in a very short period," Professor Michael Baker says.
"That's where you can get quite an explosive outbreak. Then there's the more benign situation where quite a few cases don't infect anyone, or not more than one person."
In a worst-case scenario, then, there may already be dozens of cases who, because there are no regional travel restrictions at level 2, might be spreading the virus in different parts of the country.
The focus then turns on what the Raglan and Hamilton case have been doing in the past week.
Have they been to big social events or indoor gatherings? What kind of workplaces do they have, and are they well ventilated? Have they been travelling?
What age groups and ethnicity are they, which can provide clues as to whether they are more likely to be social butterflies, or live in larger intergenerational households?
Even if the answers to these questions are on the brighter side, a precautionary approach would be to put the region into level 3 as soon as practically possible.
The cases will also put the spotlight on the Auckland boundary defences.
Thousands of essential workers who can travel out of Auckland need to be tested once a week, and while that is clearly useful, nothing is 100 per cent foolproof.
That has already been apparent with the truckie who drove from Auckland to Palmerston North who tested positive yesterday, and is now isolating in Palmerston North.
So the other focus is how the protections at the Auckland boundary can be strengthened.
One way to do that would be to shift Auckland back to level 4, which would reduce traffic over that boundary.
In any case, the Waikato cases show there are still undetected chains of transmission, and not only in Auckland.
Moving Auckland to level 2 this week - which seemed a real possibility on Friday, with the boundary kept in place - now seems extremely unlikely.