There are now 67 confirmed cases of measles in New Zealand, and 52 of these cases are in unvaccinated people.
Only seven occurred in people who were fully vaccinated against the disease.
The other eight cases occurred in people who were partially vaccinated.
"As expected, the majority of cases are in unvaccinated people," said public health physician Dr Jill Sherwood.
"While some of the cases are in vaccinated people, most of them have only received one dose."
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The MMR (measles, mumps and rubella) vaccine needs to be taken in two doses in order for it to be effective.
"Almost two thirds of the cases are linked to the current outbreak in Canterbury," said Dr Sherwood in a statement.
The current outbreak is not as large as previous ones, according to Senior Lecturer of Vaccinology at Auckland University, Dr Helen Petousis-Harris.
"We had a whopper in 1991 with thousands of cases and seven deaths, and then managed to stave off another in 1997 with a mass vaccination campaign," she said in a statement.
But this doesn't mean we're safe.
"With the global resurgence of this disease, we can expect more measles cases getting off a plane and walking through our communities," Dr Petousis-Harris continued.
Measles is highly contagious, and anyone who contracts the disease will be highly infectious for five days either side of the appearance of the rash.
Anyone who is unvaccinated and has come into contact with a measles patient is urged to quarantine themselves for 14 days.
This means avoiding public places such as schools, or public gatherings as the disease is particularly dangerous for pregnant women, babies and cancer patients who cannot be vaccinated.