Education Minister Chris Hipkins has labelled parents who don't have their children vaccinated "pro-plague".
Hipkins told reporters today that Northland DHB needed to step up in its responsibility on immunisations in the region.
"Clearly there is an issue there that the DHB needs to address," he said.
"I don't believe that kids should be denied their right to an education, particularly if it's a conscious choice by their parents not to immunise.
"Those kids actually are the ones who most deserve to learn about science.
"Children shouldn't be excluded from their education because their parents are pro-plague."
When asked what he meant by the term, Hipkins said "Those people who are anti-vaccination are by definition pro-plague."
His comments follow news that Northland health authorities have asked schools to consider sending children home for at least two weeks if they have not been vaccinated against measles.
The move could affect about one in every six Northland schoolchildren.
DHB chief executive Nick Chamberlain wrote to Northland principals yesterday saying the region's first two cases of measles had been reported in the past few weeks and there was a 95 per cent chance that any child with measles would pass it to other children within 1m of them.
He asked schools to check whether their students had been immunised and ensure all unimmunised children and staff received a measles, mumps and rubella (MMR) vaccination.
"Please consider excluding unimmunised children during this period of high risk, i.e. at least the next two weeks," Chamberlain wrote.
"I understand if exclusion seems too harsh or has too many unintended consequences or you simply just don't want to go there. So, if this is not possible, unimmunised children that are unwell with fever, a cough or cold, must be kept away from school as it could be the early [pre-rash] stage of measles."
Tai Tokerau Principals Association president Pat Newman said about 250 of the 400 students at his low-decile Hora Hora School in Whangarei had not provided their immunisation records to the school.
"When we enrol, we ask for them repeatedly," he said.
"Generally someone says we've lost them, and I can understand that to be honest."
He has asked the DHB to check its immunisation records for all the children who have not provided records already, and will then ask parents whose children have not been immunised to take their children to their doctor to get the jabs.
"I'm reluctant to send them home, but at the end of the day I've got to look at what's best for the whole school," he said.
He was waiting for advice from the Ministry of Education about whether schools had the legal power to exclude children on health grounds unless the DHB's medical officers of health invoked their legal powers to send children home.
The DHB has not yet taken that step.
Health Minister David Clark said the two cases in Northland had come from overseas and were not related to the other New Zealand cases.
But he said anti-vaxxers needed to be challenged.
"I do have serious concerns with people who put others at risk, particularly vulnerable members of our community. The science is very clear about the benefits of vaccination," Clark said.
He agreed that children should not be punished for the actions of their parents but took the DHB to task, saying it needed to do better.
"I want to see a plan from them about how they're going to lift the immunisation rates. It alarms me when I hear stories of 200 kids at a school not being immunised.
"If that's true, the DHB needs to be in that school, offering to vaccinate those children."
Prime Minister Jacinda Ardern said Hipkins was making the point that people put others at risk by choosing not to vaccinate.
Ardern said making children stay away from school was not the way to protect them and others.
"We want them all to be in school. Ultimately, the best protection is vaccination.
"We've got to make sure that DHBs are focused on reaching as many children as possible."
Ardern said false information that vaccinations were not safe was damaging.
"Parents, I just encourage you, please vaccinate your children."
Environmental Science and Research (ESR) says 111 cases of measles were reported nationally between January 1 and May 3. Only eight of those affected were fully vaccinated.