Three new community cases of COVID-19 this weekend will give Prime Minister Jacinda Ardern food for thought as she considers axing restrictions in New Zealand on Monday.

The fresh cases are not linked to the Auckland cluster that saw Ms Ardern send New Zealand’s biggest city into lockdown last month.

Instead, health authorities say they are three members of the same household, with the link appearing to be a family member who recently returned to NZ.

What has contact tracers puzzled is that he underwent quarantine without recording a positive result.

The man travelled from India to New Zealand on August 27, completed his mandatory isolation in Christchurch before returning to his home in Auckland.

On developing symptoms, he was tested, and on returning a positive result, his household members were isolated and tested – picking up the two further positive results.

It remains to be seen if the outbreak will spark a fresh cluster.

Health authorities have two working theories on how the man brought the virus into the community despite his fortnight in isolation.

The first theory is he caught COVID-19 overseas or on his international flight, and had an above-normal incubation period, developing symptoms after three weeks.

Developing symptoms after more than two weeks is considered rare.

The second theory is he was infected on his flight from Canterbury to Auckland after completing his isolation.

This has led contact tracers to contact all passengers on that Air New Zealand flight.

A connection to the existing Auckland cluster has been ruled out by genomic testing.

The notion of a new cluster will be the major concern for Ms Ardern as she considers adjusting New Zealand’s alert levels.

Auckland’s 1.6 million inhabitants endured a 16-day lockdown in the aftermath of last month’s cases, but the city is now at alert level two – like the rest of New Zealand – but with smaller cap sizes for gatherings.

Last week, Ms Ardern pledged to rid all restrictions for the rest of New Zealand should cases “track as they are, and maintain the containment we have seen”.

The Auckland case numbers seem to tick that box, given there were four community cases in the past week, compared with 18 in the previous week.

Outside of Auckland, there have been no cases found in months – except for a handful of cases in Tokoroa with established links to Auckland businesses.

The Tokoroa cases also produced two of three deaths due to COVID-19 this month, with NZ’s overall death toll at 25.

New Zealand’s cabinet will meet on Monday morning to make a decision on restriction levels before Ms Ardern announces the decision.

-AAP