Anyone travelling to Auckland is being told they must be immunised against measles, as the country deals with its worst epidemic of the highly contagious disease in 22 years.
There are at least 849 cases of measles nationwide, with 731 of these in Auckland.
The Ministry of Health says babies travelling to or living in Auckland must also have the jab.
And the regular 15-month vaccinations including M=M=R have been brought forward to 12 months.
Meanwhile, health officials are scrambling to identify people who travelled on an Air NZ flight from Samoa to Auckland - with an infected person; that flight was nine days ago.
The centre of the outbreak today is Manurewa High School in South Auckland, which has 13 new cases.
The school sent 300 students home and told families to keep their children at home today if they can't show they are immunised.
One mother told RNZ she was happy with the level of communication with the school and parents.
"Definitely, even in other schools around, notices are going out, emails, texts, it's awesome."
Principal Pete Jones said the first case was weeks ago, but he didn't see the outbreak coming.
"It just got to a scale and a level that it was really difficult to manage from a logistics point of view," he said.
"As I say, 300 students sent home."
Students not immunised have to stay away until Monday, call the school and state they are not immunised.
Mr Jones said nurses from Counties Manukau would be in the school giving shots to those who hadn't had them next week, but the difficulty was trying to find who had them and who hadn't.
"In theory yes and we have asked for it, but the challenge is, is the data accurate?" he said.
"And what's proving through this exercise is that data isn't accurate."
Homai Primary School and early childhood education centre is a stone's throw from the high school.
Principal Rosina Wikaira said the phones had been running hot, but her records were tight - there's only one student not immunised and this student will receive it today.
"Don't panic, but please do keep your children home if there's any symptoms," she said.
"Another letter is going home today in support of our high school, because a lot of our [students] they have older siblings at the high school, so of course they're in the same home. We're just making sure that if they're the same families, keep them at home."
Mr Jones said he had sent two staff members home as a precaution, and the school has had to cancel events due to the outbreak.
"We had an awesome event planned tonight with all the Auckland Mayoral candidates coming to school, which we were really looking forward to, and which had been organised and planned by our students," he said.
"But unfortunately with all the circumstances we've had to say no to that."
Mr Jones said it was inevitable there would be more cases.