New and worrying cases have emerged in New Zealand’s Delta outbreak as Jacinda Ardern’s government mulls a lockdown extension.

At 3pm NZST, Ms Ardern will release her decision on whether to extend the lockdown beyond current plans.

The lockdown, announced on Tuesday night after just one case, is due to end on Friday for all of NZ except Auckland and the neighbouring Coromandel region.

They will stay in lockdown until at least next Tuesday.

As of Thursday lunchtime, the outbreak stood at 21 cases.

Health authorities and COVID-19 modellers expected there were many more Delta infections in the community, awaiting detection through testing, and word of other cases is trickling out.

On Friday morning, Associate Health Minister Ayesha Verrall, an infectious diseases physician drafted into government by Ms Ardern, confirmed a new case visited two Auckland hospitals.

The young man is at Waitakere Hospital but spent time at North Shore Hospital, possibly while infectious.

“Action is taken at both hospitals to ensure the safety of the staff and patients there,” Dr Verrall said.

Three Auckland schools have had staff or students test positive to the virus. On Friday morning NZ Post confirmed an employee at an operations centre in eastern Auckland had the virus.

Case data will be before Ms Ardern’s cabinet on Friday as it decides on restrictions.

The decision is nuanced.

All observers believe Auckland’s lockdown will be extended beyond the original week given the emergence of cases and the large number of locations of interest.

The Coromandel, a holiday peninsula popular with Aucklanders who take the two-hour drive east, also went into a week’s lockdown after Case A visited the region.

Additional cases are yet to emerge there, and wastewater testing has not shown evidence of the coronavirus.

A stronger argument can be made to lessen restrictions for the rest of New Zealand.

Many on the South Island – which has not had a community case of COVID-19 for more than a year – feel they should be unburdened from lockdown.

Dr Verrall said the government needed to see not just absence of the virus across New Zealand but proof of its absence through strong testing rates.

On Thursday, Ms Ardern announced a genomic link between Case A and a Kiwi who travelled from Sydney on August 7.

COVID-19 modeller Shaun Hendy, who originally predicted about 100 community cases from the outbreak, downscaled his prediction to a “few dozen” after that find.

“We still need to be cautious because we have had a number of exposure events over the weekend so we may well see quite a few secondary cases,” he told Newshub.

-AAP