As Canterbury residents queue up for the measles vaccine and Aucklanders are being put on alert, critics are buying tickets to an anti-vaccination workshop run by a high-profile Australian blogger.
But public health experts warn the rest of the country is just as vulnerable to an outbreak.
At least 27 people in the Canterbury region have already contracted measles, with a further 20 suspected cases being checked. Meanwhile, vaccine supplies which were supposed to last a month were used up in two days.
Today, the Auckland Regional Public Health Service warned people in the region to keep an eye out for symptoms after an infant and a young adult were diagnosed with measles.
At the same time, tickets are on sale to Taylor Winterstein's anti-vaccination workshop, Making Informed Choices, which is being run in Auckland in June.
Director of the Immunisation Advisory Centre Nikki Turner said while Cantabrians were dealing with the current situation, the whole country was equally at risk of an outbreak.
Measles is a serious disease with one in 10 people needing hospital treatment. The most serious cases could result in deafness or swelling of the brain.
She said there was "a huge group of people" in their middle ages and late twenties who would not be fully vaccinated and which was allowing the spread.
The MMR vaccination was introduced in 1969 but it was common practice for people to only get one vaccination up until about 1990.
New Zealand declared it eradicated from the country in 2017, meaning all new cases came from overseas and spread among those who were not immunised.
University of Otago Professor Michael Baker, who is based in Wellington, said vaccination rates around the country were very similar, meaning an outbreak similar to that seen in Canterbury was possible in any region.
At the end of last year, 88 per cent of 5-year-olds in New Zealand were fully vaccinated against measles, mumps and rubella, Baker said. The rates in Auckland and Canterbury were similar at 86.6 per cent and 92 per cent respectively.
"Measles is an infectious agent that will always find a gap if there is one," he said.
Experts agreed an immunisation rate of 95 per cent was needed before all outbreaks could be stopped, meaning New Zealand was going to continue to see small to medium outbreaks for some time, Baker said.
But both he and Turner said they were not overly worried about the upcoming anti-vaccination workshop being held by Winterstein.
Winterstein is a blogger, mother of two, wife of NRL star Frank Winterstein and qualified Integrative Nutrition Health Coach.
She made the decision not to vaccinate her children and the $200 workshop promises to provide information and research about vaccinations.
"The benefits of vaccines are constantly over-exaggerated and the risk of an adverse reaction severely downplayed," she writes on her website.
Turner said immunisation rates were increasing and the hesitancy around vaccinations which first reared its head in the 1990s was dropping away.
She said she was in favour of allowing people to come and have their opinions heard but warned it was a "historical issue that's been well and truly put to bed".
"They are making a living and a business out of recycling these issues."
Baker said the event was a "minor concern" but the number of anti-vaccination supporters was small.
"There isn't anything new in this fringe science," he said. "It's not around the science or even common sense anymore. As an epidemiologist, and even as a parent, you only have to look around to see the benefits of vaccines."
All the studies, including a study of more than half a million Danish children which was release last week, were showing vaccinations were safe and did not increase the risk of children developing autism. "I think people can feel very comfortable about the safety."
• The first priority for Canterbury was to vaccinate children aged 12 months to 13 years and people aged 14 years to 28 years who had never been immunised.
• People who have had one dose of MMR or one measles vaccine were considered to have a good level of protection.
• If you think you have the measles, call before visiting your doctor to avoid spreading the virus in the waiting room.
• Stay away from work, school or public places if you think you might have the disease or if you or a family member aren't fully immunised and may have been in contact with someone with measles.
• The first symptoms of measles include a dry cough, runny nose and headache. This is followed by a blotchy rash.
• If you catch measles you're infectious five days before and until five days after the rash appears.