There are six new cases of Covid-19 in New Zealand, all of which are linked to the Mt Roskill "mini-cluster", director-general of health Ashley Bloomfield says.

A baby boy and three other children are among the six cases.

The total number of cases linked to the mini-cluster - connected to the Mt Roskill Evangelical Fellowship Church - is now 43. There is a smaller cluster of 14 within that, linked to a funeral.

Bloomfield said it was a series of bereavement activities, including visits to households and a funeral of September 7.

All the close contacts, including all 48 people at the funeral, from those events are in isolation and are being tested.

Bloomfield said the new sub-group of 14 were infected by someone who went to the bereavement activities but didn't know they were infected.

He said there was some reluctance from the Mt Roskill mini-cluster to be tested at first.

Police disperse illegal mini-cluster meeting

He said there was a meeting of mini-cluster people on August 15, when Auckland was in level 3, and police had gone and asked that meeting to disperse.

Bloomfield said the size of the group associated with the Mt Roskill mini-cluster had grown by hundreds since it was detected - there were 108 contacts identified with the bereavement activities alone.

He did not know how many had been infected in the community who weren't isolating, but he added that most of the infected cases had been household contacts.

Bloomfield said many in the church group had been tested, but was now asking all members of the fellowship to be re-tested.

"People should be tested even if they have no symptoms."

Bloomfield said the wider testing of those involved in the church was about containing the wider outbreak.

Bus driver tests positive

Another case reported yesterday, also part of the new sub-cluster, was a driver on the northern express bus service. That bus travels between the central city and at least as far as Albany.

Auckland regional public health said there were no close contacts on the relevant bus journeys, and the driver was not symptomatic at the time, but was also wearing a mask.

HOP card data will also be used to identify passengers as a precaution, he said.

The public health unit will later reveal details of the bus journeys.

Since August 11, the contact tracing team has identified 3346 close contacts of cases, of which 3305 have been contacted and are self-isolating.

There are 74 people linked to the community cluster who remain in the Auckland quarantine facility, which includes 58 people who have tested positive and their household contacts.

Today there are four people in hospital with Covid-19.

Two are in ICU, one at North Shore and one at Waikato hospital.

There are now 125 active cases in New Zealand. Of those, 43 are imported cases in MIQ facilities, and 82 are community cases.

Yesterday 8363 tests were processed.

Bloomfield said contact tracers needed to be able to trace people quickly to stop Covid-19 from rapidly spreading, but they depended on people sharing where they've been and who they've been with.

There are now 2,161,200 users of the NZ Covid Tracer app, which is being updated again today to make scanning QR codes easier.

A false positive in Christchurch was someone who traveled to New Zealand for the terrorist sentencing. He spent 14 days in manged isolation and then had two further tests.

Bloomfield said the person tested positive at a community testing centre, when the "strong impression" was of an old infection.

Rydges Hotel maintenance worker

Bloomfield said the maintenance worker at Rydges Hotel was likely infected in a one-off event by using the elevator at the hotel. The case is now closed. No close contacts tested positive.

High school student tests positive

Last night, a student at St Dominic's Catholic College was confirmed as having Covid-19.

The student at St Dominic's was at the bereavement activities, Bloomfield said.

All members of the school community will be tested because there could have been in contact in the corridors.

Schools with students who either travel on buses into the area or share close family connections are telling parents to take a cautious approach to the unfolding Covid situation.

Health Minister Chris Hipkins revealed this morning that the student was a previously undisclosed close contact of the Mt Roskill mini-cluster.

He added that the mini-cluster had been "challenging" because some within it "don't accept or haven't previously accepted the science", and police had been brought in to ensure we're "getting the sort of cooperation we really need".

A person who works at Auckland's Māori public health unit, Hapai Te Hauora, has also tested positive.

A letter sent yesterday from the Auckland Regional Public Health Service to those working in the Whānau Centre building, where the infected person works, says a person at Hapai is now a confirmed case.

Yesterday there were six new cases of Covid-19, two in managed isolation and four linked to the Mt Roskill Evangelical Fellowship Church group.

There were four people in hospital including two were in ICU.