The Ministry of Health and Prime Minister Jacinda Ardern believe the remand prisoner who recently tested positive for Covid-19 was infected in Auckland after leaving prison.
Three people, including two children, tested positive for Covid-19 in the Waikato region late last night.
One of the children was symptomatic while at Mangatangi School on the Hauraki Plains last week. The school has now closed. Parents and students are being tested and the three household contacts are being moved to quarantine.
The family is linked to a remand prisoner who was at Auckland's Mt Eden Corrections Facility and was released on e-monitored bail to a house in the Firth of Thames on Wednesday, September 8 - when Auckland was still in alert level 4 lockdown.
Ardern said the prisoner had been in a Covid-19-free environment (prison) prior to release on bail, so checks were being made on the transport to that prisoner's home.
"It's clear this person has been infected by someone involved in their transport to the bail address."
Ardern said it was likely the prisoner got it from somebody involved in transporting him to his home. Corrections staff had not transported him.
Director-general of health Dr Ashley Bloomfield said genomic sequencing was still coming, but it seemed likely the prisoner had infected the other members of his household.
The ongoing investigation from Auckland Regional Public Health is looking to establish epidemiological links to the wider Auckland outbreak.
The Ministry of Health said they are confident there has not been infections in the community as five other household members isolating at home returned negative results yesterday.
Today, a drive-through testing centre was set up at Wharekawa Marae, and will also be open on Tuesday from 9am.
Since 2pm the centre has processed 340 swabs. Waikato DHB Chief Executive Dr Snee said all tests would be fast-tracked with results expected late tonight.
"Our advice to the local community is to exercise an abundance of caution at this stage. If you are able to stay home, please do. For those who do need to go out, please take extra care to wear a mask, practise social distancing, and wash your hands regularly."
Mangatangi School has now been named as a location of interest on the Ministry of Health website.
It relates to Wednesday and Thursday last week from 8am to 4pm.
Anyone who was at Mangatangi School is told to self-isolate for 14 days after being exposed at this location of interest.
"Test immediately," is the official advice from health officials. The affected day is last Wednesday, September 15.
The majority of the new community cases reported today are located in Auckland, while three are located in Whakatīwai.
Mangatangi School is a small rural school and had 109 students on its roll at its last Education Review Office report in 2020.
The school is in an alert level 2 area and had been open to students.
Local MP Scott Simpson told Newstalk ZB's Kate Hawkesby the small rural community is worried by the news that's come through overnight.
"People are naturally worried. Mangatangi is a small community, a tight-knit community, a community that cares and looks after itself, but people are naturally worried and very concerned.