Three hundred students have been sent home from an Auckland high school as the measles outbreak worsens.
And a lecturer in vaccinology says it is inevitable that more students and staff at Manurewa High School will be diagnosed.
• Auckland high school cancels mayoral event due to measles outbreak
• Kiwi mother shares ordeal after 7-month-old catches measles
• Vaccinations at Auckland churches and shopping malls being considered in fight against measles
A total of 13 students have so far contracted measles and the school has told anyone not immunised to stay home until Monday, and for those attending to bring proof of immunity.
A public notice put out by the school said the confirmed cases had led to 300 students being sent home and all school and related community activities being postponed until further notice.
The board of trustees has also decided that each student must provide proof of their measles, mumps and rubella (MMR) immunisation status.
Board chairman Stephen Smith said: "If you have been immunised, please bring proof of your immunisation - Plunket Book or record from your doctor. Go to your normal period one class and your teacher will take a copy for our records."
Those students who are not immunised are being told to contact the attendance office to let them know and to specifically give them the reason "not immunised".
"You will be recorded as not immunised and if there are any further confirmed cases, there is a possibility that you could be sent home for up to two weeks," Smith said.
The secondary school is now working closely with the Counties Manukau District Health Board which is due to offer immunisations at the campus over the next fortnight.
Yesterday, the Government updated the total number of cases of measles so far this year to 849, making it New Zealand's worst measles epidemic in at least 22 years.
The University of Auckland's senior lecturer in vaccinology, Dr Helen Petousis-Harris, expects more people to contract the disease at the school.
"It'll be inevitable because people are infectious before they develop any symptoms. So they could have been moving among other members of the school community and also outside that school community for some time before it was recognised that they had the measles," she said.
"We're talking about the most infectious disease that is known to man."
She said we can expect things to get worse before they get better.
"It looks to me like it's ramping up - the epidemic curve looks like it's heading into interstellar space at the moment. So there's no evidence that it's levelling off at this stage, which is really concerning."
Just down the road from Manurewa High, Rowandale Primary School has also been rocked by the outbreak.
A teacher there was diagnosed with measles just over a week ago and school principal Karl Vasau said they're remaining vigilant for signs of the measles.
"We've got 610 children at Rowandale School and when this scare started and we started to make measures for children who aren't immune, we had about 170 children away on the day after that. We also had a large number of our staff away."
Auckland medical officials say the regional public health service is helping the school try to stop the spread of the virus.
Nationally, the Ministry of Health is boosting support for immunisation services tackling the measles outbreak.