No further cluster cases today and tomorrow could suggest a "reasonable chance" that Auckland's lockdown snuffed out any virus still in the community, a Covid-19 modeller says.
Cabinet ministers tomorrow face a "complex" decision over Auckland's alert level settings - and will be wary of another yo-yo into lockdown if the Valentine's Day cluster isn't properly stamped out.
Minister Peeni Henare today said the country would have to stay at least three more days in current alert levels, despite another night with no new community cases.
Kiwis will have to wait until after tomorrow's Cabinet meeting before finding out if Auckland will drop out of level 3 and the rest of New Zealand out of level 2 from 6am on Sunday.
No new fresh cases in the cluster have been recorded since "Case O" - a household contact of four other cases, who has been in quarantine since February 23 - was reported on Sunday.
"That's definitely a promising sign," Te Punaha Matatini modeller Professor Michael Plank said.
"And the longer we go with no case, the better it looks. If we get no new cases coming up today and tomorrow, there's a reasonable chance that, if there were any other cases, Auckland will have been in level 3 by the time they became infectious."
The incubation period of the Sars-CoV-2 virus - that's the time between exposure to the virus and symptom onset - could sometimes be as long as 14 days, but it typically averaged five to six days.
"So hopefully, that will reduce the chance that they would have passed it on."
More than 16,000 tests were processed on Tuesday, as Auckland opened 11 new testing community centres to meet a surge in demand.
"If we are testing the right people - and they continue to come back negative - then that's a pretty good sign that this particular cluster hasn't spread further," Plank said.
"But it's especially important that we test those close and casual contacts that the ministry has identified."
More than 98 per cent of casual plus contacts of "Case A" at Papatoetoe High School have tested negative, after being retested.
A further 33 "close plus" contacts at Kmart Botany, where another of the cluster cases worked, had also returned negative tests, as had 1823 of 1868 people who reported being in the store at times of interest.
But Plank said there was still a risk to consider.
"I think the thing that will make [Cabinet ministers] cautious is that we really want to avoid a yo-yo back up the alert level - so they may conclude it's worth staying the course for those extra few days," he said.
"It's a complex decision, because there are now also questions over whether people are following the rules, or staying home when they should be. That would probably be weighing into the decision as well."
Te Punaha Matatini modelling expert Professor Shaun Hendy today told broadcaster Mike Hosking that he believed if there were no new community cases today and tomorrow the Government would likely reduce alert levels.
There was a sting in the tail of the initial outbreak with a three-day lockdown not sufficient to close it out.
The latest seven-day lockdown was the Government making absolutely sure to shut it down with confidence.
"The one thing we know with this B.1.1.7 variant, you really don't want to let it get out of control," Hendy said.
"It spreads more rapidly and does take a lot of work to control it so my calculus is these shorter, sharper lockdowns to bring these new variants under control is probably worth it in the long run."
He said it was a super-spreading virus so while four out of five people who get infected would only impact household or very close contacts, the fifth person would spread it far and wide.
"It was a good sign yesterday that none of the very large number of tests processed on Tuesday came back positive," Hendy told Hosking.
"That's an excellent sign and we'll be hoping we see the same thing today."
He said we were proving to be "lucky" in this latest outbreak.
There were a number of potential exposures to a positive case last week and so far it appeared there had been no infections as a result.