More than 1800 people have been infected with the highly virulent disease in the present outbreak, about 1500 of them in Auckland alone. Measles has the ability to weaken the body's immunity to other diseases and can even be fatal. 

Appearing on The AM Show on Monday morning, Genter defended the Government's efforts to control the virus' spread. 

"If you look at the first 10 months of this year, already we've administered over 300,000 vaccines. We've got another 107,500 being distributed around the country right now and another 155,000 coming in the next few months."

Shortages have remained, however, which Genter blamed on an "unprecedented number of people looking to get vaccinated" in a two-week stretch in September.

Measles cases have been rising worldwide over the past few years. In the first three months of 2019, there were four times as many cases than in the first three months of 2018. 

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Asked if the initial response here in New Zealand was too slow, Genter blamed a lack of funds initially available.

"This sort of thing takes time to build up. Our readiness to preparedness to respond is actually several years in the making, and that's why it's so important... to properly fund our health system," said Genter.

"Anyone campaigning on tax cuts is basically promising that we'll run down public services in the future, because the reality is New Zealand - to be like other developed countries with good levels of services and infrastructure - needs to be able to pay the people who do that work, needs to be able to hire the people who go out and do the immunisations."

Herd immunity for measles is estimated at about 95 percent immunisation coverage - this is the level at which the disease struggles to spread through the general population because of a lack of unimmunised hosts to infect. Ministry of Health data shows only 88 percent of present-day children are fully immunised, and some Generation X/older Millennials might not be immune at all due to historical gaps in coverage. 

"It's really important that there is a full review, that we do everything we can to respond to the outbreak now to ensure it doesn't spread further and to catch up and get back to. In fact, I don't think we've ever been at herd immunity, certainly not in the recent past.

"So we do need to get up to herd immunity. Measles is extremely contagious and there have been higher levels of measles worldwide. We were responding to it, but clearly, we need to respond to it at an even greater level."

Genter said there are presently enough vaccines to ensure everyone under 15 is able to get immunised. A catch-up campaign for young adults is planned for "early next year".

"Pharmac is out there getting all the vaccine that is available, and as much as we can possibly get."

According to the World Health Organization, New Zealand has been technically measles-free since 2017 - that means there are no homegrown outbreaks, and any outbreaks caused by someone bringing the virus into the country is eliminated within 12 months. 

New Zealand has until March next year to end the present outbreak to retain that status, vaccinologist Helen Petousis-Harris told RNZ in August.

National has not said whether it would cut taxes if elected in 2020, but it's likely. The party's promised tax cuts at the 2017 election didn't come to pass because it lost.