Experts reveal what could stop the country dropping COVID-19 alert levels

Craig McCulloch for RNZ

Experts have warned of a few sticking points that could hinder parts of the country from shifting down alert levels this weekend.

On Monday, Prime Minister Jacinda Ardern signalled alert level 4 would expire at midnight tonight everywhere except Auckland.

Cabinet ministers are meeting today to decide whether to go ahead with that plan or to once again extend restrictions.

University of Otago epidemiologist professor Michael Baker said the public information, to date, painted a "reassuring picture" outside of Auckland.

As such, he said a shift to alert level 3 in the near future would seem "pretty reasonable" as long as mask use remained mandatory.

Baker said high levels of community testing and wastewater testing would act as safeguards.

"The risks of dropping down too early ... are partly covered by the fact that you can detect cases if they occur and go back to level 4 if necessary," Baker said.

"No one wants to do that, but I think we're fairly close to the point where we could do that with a reasonable degree of safety."

Cabinet would have to decide where to draw the geographic boundaries between different alert levels, Baker said.

One option would be to split the country in two with different levels for the North and South Islands. Another would be to draw a ring around the Auckland region.

Baker said it was difficult to make predictions without more detailed information from the Ministry of Health.

He said the ministry should disclose every day how many of the new cases were isolating, how many were essential workers, and how many were rulebreakers.

"If you're sitting at home, or if you're looking at the Ministry's website, there isn't a lot of information to guide risk assessment," he said.

"We're a nation of epidemioligists now ... it's not that hard to make [the data] a lot more intelligible."

Baker said he'd also like confirmation that all new cases were being linked to existing cases or occurring from manageable "exposure events".

Any unexpected cases would be an ominous sign control of the outbreak being lost due to unknown chains of transmission, he said.

University of Canterbury Professor Michael Plank said he had considered it likely, up until yesterday's media update, that the country outside of Auckland would move down alert levels at midnight tonight.

However, he said he was concerned by news that Covid-19 had been detected in Christchurch's wastewater.

"It is not definitive," Plank said. "It could be that it is linked to cases in MIQ, but it seems like a bit of a coincidence. I think the government will want to look at that."

Officials confirmed yesterday there were three Covid-19 cases in managed isolation and quarantine facilities in the city which could explain the result.

Plank said the government may delay any alert level change until early next week to wait for a few more days of data.