There are concerns anti-vax behaviour is putting children at risk.
A Northland daycare centre has closed temporarily with a fifth case of measles confirmed in the region.
Early Childhood Council chief executive Peter Reynolds is urging parents to act responsibly and get their kids vaccinated.
"We have a law that actually says it's a matter of choice," he told Newshub. "What we've got to make sure of though is we're not being scaremongered into a particular behaviour because of information that's being provided to us which is not entirely accurate."
Northland DHB says more than 100 people may have been exposed.
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"If a parent chooses not to immunise their child, that has repercussions - and one of the repercussions that they just need to understand, is that if a contagious disease does hit a childcare centre, those unimmunised children need to go home," said Reynolds, adding that it shouldn't be a difficult choice to vaccinate.
"None of that stuff is as hard as facing up to looking at your child in a hospital bed, suffering from measles, because what can come from that can permanently affect them."
Vaccine avoidance has been named one of the greatest threats to health worldwide by the World Health Organization.
Anyone who suspects they have contracted measles is urged to stay away from emergency departments and doctors.
They are asked to call Healthline of 0800 611 116 to speak to a registered nurse.