Dr Ashley Bloomfield says the 15 new cases are made up of six confirmed cases and nine probable cases. Twelve people are in hospital, three are in ICU and two are in a critical condition.
Principals are warning the government's plans for partially reopening schools at alert level 3 will be a shambles.
They warn that teachers will struggle to teach classes in-person and online, social distancing will be nearly impossible to maintain, and parents will send children to school simply because they are sick of having them at home.
The government has outlined details of conditions under alert level 3 ahead of a decision on Monday whether to lift level 4 lockdown.
It wants parents who return to work during level 3 to be able to send their children to early childhood centres and schools because they cannot legally allow children under the age of 14 to stay home alone.
It says children should stay home if they can at level 3 , but there will be no checks to ensure only parents who cannot work from home are sending their children to class.
Otorohanga College principal Traci Liddall said she could see potential problems with the government's plans.
"It's going to be a shambles. Who is allowed to come back? What is the purpose of them coming back? Are they just coming back because parents are sick of them? Are they coming back because they are the children of essential workers?" she said.
The president of the Auckland Secondary Principals Association, Richard Dykes, said teachers would not be able to provide an in-class lesson for students who were present in person and a remote lesson for those studying from home.
"If students do turn up, they're going to be working online, maybe with some teacher oversight, but certainly it won't be face-to-face teaching as we know it," he said.
Dykes said he expected most students would stay home.
The president of the Principals Federation, Perry Rush, said principals needed a lot more detail about how partial reopening would work.
He said there would be challenges with maintaining social distancing at schools.
"That is always a really difficult challenge in any school and it will largely be impossible," he said.
Early childhood centres were included in the level three plans and Peter Reynolds from the Early Childhood Council said they had a lot of questions.
Reynolds said social distancing between children and teachers in early learning centres would be impossible, but they were used to good hygiene measures.
"They will continue to ensure children are washing their hands regularly, they will continue to use hand sanitisers," he said.
"All of things they had in place to minimise the impact of Covid before the lockdown, they will continue to have in place afterwards."
