Health experts have confirmed the number of measles cases in New Zealand has risen above 1000.
A Ministry of Health spokesman told Newshub there are now 1051 cases of the infection - 877 of which are in Auckland.
Immunisation Advisory Centre director Dr Nikki Turner says it is a "very sad" milestone to reach.
"This was entirely predictable and preventable, so it is very disappointing for us.
"I guess on the other side I have to say New Zealanders are responding really well to this.
"We hear this week there's been a huge uptake of people coming to get vaccinations."
Dr Turner said everyone is aware that it is a "significant problem".
"So, [it's] very disappointing that we have to create a disease before we create demand."
Dr Turner said people need to get children and adults, particularly in the Auckland region, vaccinated as soon as possible.
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Meanwhile, it has been confirmed a person on a flight from Auckland to Melbourne last Friday was unknowingly infected with measles.
The flight - Air New Zealand flight NZ123 - departed Auckland about 8:45am on August 30.
People who may have been in contact with that person should be vigilant for symptoms, Auckland Regional Public Health Service medical officer of health Dr William Rainger said.
Measles is one of the most infectious viruses out there. Just being in the same room as someone with the disease is enough to catch it.
There are numerous reasons why people might not be immunised - one of those is a fear of needles. University of Auckland infectious disease specialist Dr Emma Best told The AM Show on Thursday that work is being done to find new ways of delivering the MMR vaccine.
No one has died of measles in New Zealand since the 1990s, but experts have said it's inevitable if the current outbreak isn't stopped. US data suggests around one or two people die for every 1000 infections.