Three of New Zealand's top Covid-19 experts say the diminishing number of Covid-19 cases announced today is a great sign as the nation attempts to battle its way out of lockdown.

But celebrations over the downward trend this week should come with some strong caveats, they all warned, agreeing we're not at a place yet to consider loosening alert levels.

"It's great - obviously very promising," microbiologist and science communicator Siouxsie Wiles said of today's announcement that there 28 new cases of Covid-19 in the community.

"I guess we just need to keep seeing that day-on-day. It's not just about any one day's numbers.

"I think it clearly shows things are working."

The Government announced 49 new cases on Thursday, which was also considered a considerable drop from recent weeks. There are currently 731 cases in the community.
Had there not been a lockdown, there would have likely been hundreds, if not thousands, more cases by now, Wiles said.

"But we also know this whole outbreak came out of one case," so it's important not to act hastily based on an incomplete picture. We just need to do it once and do it properly."

University of Otago epidemiologist Michael Baker agreed.

"Looking at cases on a daily basis of any disease, it always bounces around," he told the Herald after today's numbers were announced. "All it would take is for one essential worker to go to a workplace and not wear a mask and you have a new cluster. So you can never read a large amount into a single day."

The trend this week was definitely "encouraging", he added, but it would be important to drill down into the characteristics of each new case as health officials learnt more about them.

If the new cases were within the same household as previous cases, if they had adhered to lockdown rules and they weren't essential workers, "you'd be feeling quite good", he explained.

University of Auckland Covid-19 modeller Shaun Hendy believes this week's numbers could potentially be light at the end of the tunnel for the region's alert level 4 restrictions.

The rest of New Zealand moved to alert level 3 earlier this week. But like his colleagues, he cautioned not to let up yet.

"We've clearly seen a downward trend this week, and that's clearly one of the things we're looking for, so well done, Auckland," he said.

Hendy said he still thinks the best-case scenario would be two more weeks of decreasing numbers before Auckland could consider an alert level shift.

"Certainly the outbreak could very well have a longer tail," he said, pointing to last year's August lockdown in Auckland, which had to be extended after several gatherings resulted in new cases.

"If this trend continues, then that two-week period should be sufficient," he said. But there's still plenty of water to go under the bridge at this stage."