Covid-19 modeller warns 'more time needed' at Level 3 as lockdown decision looms

A data modelling expert is calling for New Zealand to remain at its current alert levels for a week longer, with the risk of undetected Covid-19 in the community still out there.

Professor Shaun Hendy told TVNZ1's Breakfast this morning any transition down alert levels is risker than last time, so the Government has a big decision today.

At 3pm, Prime Minister Jacinda Ardern will announce if and when Auckland is coming out of Covid-19 Alert Level 3, and how long the rest of the country will remain in Level 2.

The decision on alert levels comes as there was  one new Covid-19 case linked to the Auckland cluster  yesterday. There were also two other positive cases in returnees from overseas - they are both in managed isolation.

While the low numbers are good, Prof Hendy said that in May when New Zealand was looking at making the same move, there were about 10 days of either no Covid-19 cases, or just one or two popping up.

"We're not in that situation yet and so that means this transition is riskier this time around," he said.

However, he added it was different with just one community outbreak and genomic information helping to track the current Auckland cluster.

Prof Hendy said it was a hard call for the Government to balance the economic impact as well, but he suggested one more week at the current levels.

"I think need more time at Level 3. We've got that additional information which will give us more confidence than we had last time, and we have had a couple of days of encouraging case numbers, but I don't think we're there yet," he said.

"Last time we talked a lot about the possibility of asymptomatic transmission and we've still got that of course.

"I think we need longer with these smaller case numbers before we can be completely confident."

Outside Auckland, there has been some Covid-19 cases in Waikato which were linked to the Auckland outbreak, however opening up domestic travel again with the city could be a risk, Prof Hendy said.

"If Auckland were to drop in alert level and Aucklanders were to start travelling again, the risks of one of those undetected chains of transmission going to another part of the country, you know, heading down to a big event down in Wellington and then kicking off a new chain, are high.

"I think the rest of the country does need to remain alert and we may need to be looking at event size restrictions going forward or some other controls that can keep us from going back into a higher alert level in other parts of the country."