Public health experts and COVID-19 modellers are urging the New Zealand government to tighten its lockdown settings to avoid losing hard-won gains in the fight against the Delta variant.

NZ health officials reported 75 new local cases of the virus on Wednesday, up from 49 on Tuesday and 53 on Monday.

Prior to announcing the figure, director general of health Ashley Bloomfield predicted cases would continue to fall but some “bouncing around” would be likely, as occurred during the country’s last outbreak.

Of the new cases, 74 are from Auckland and one, likely to be a historical case, is from Wellington.

The new cases take the overall outbreak to 687.

Hospitalisations remain steady at 32, with eight patients in intensive care units and three on ventilators.

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Dr Bloomfield told television station Three the outbreak had likely “hit the peak a few days ago”, with 83 infections confirmed on Sunday.

“People shouldn’t worry if it does go up again. The key thing is we’re on our way down,” he said.

Experts share Dr Bloomfield’s optimism – but caution against weak spots among New Zealand’s current settings.

Nick Wilson, a professor of public health at the University of Otago, called recent drops “encouraging”, noting the lower proportion of transmission in the community.

However, he notes with concern recent reports of three infections at an Auckland chicken-processing factory.

“The Delta variant is very infectious and so you could have a problem with an essential worker, causing infection in a workplace, so we could still have a super spreading event,” he said.

“We’ve seen very big outbreaks in meat processing plants in the US with atmospheric conditions in these factories and people being in close proximity.”

He recommends an upgrading of workplace mask-wearing rules.

On the weekend, Ms Ardern also foreshadowed a tightening of workplace restrictions, but on Wednesday COVID-19 Minister Chris Hipkins said the government was happy with its current settings.

“We review information every day … we haven’t made further decisions on that yet,” he said.

Dr Wilson cautioned against complacency.

“The government has been very slow on masks and it still hasn’t mandated at the alert level four for masks in factories and office workers who are essential workers. That is one of its biggest mistakes, unfortunately,” he said.

Among Dr Wilson’s other suggestions are prioritising vaccination of essential workers and reducing worker numbers at businesses allowed to operated.

Respected COVID-19 modeller Shaun Hendy, a physics professor at the University of Auckland said he was pleased to finally see a downwards trend in this outbreak, predicting “ups and downs” in case numbers this week.

Dr Hendy agreed workplaces could be New Zealand’s achilles heel.

“Workplaces remain a risk. It’s where people are routinely in close contact and it poses the most risk. Compliance at level four could still be an issue,” he said.

Also on Wednesday, Ms Ardern’s government reduced restrictions for many New Zealanders.

After a fortnight at level four lockdown, Jacinda Ardern’s government lowered all places south of Auckland to level three, allowing most Kiwis the luxury of takeaway food.

Health officials also confirmed another bumper day of vaccinations, with 84,971 doses administered – around 1.6 per cent of the population.

-AAP