In 1969 measles vaccine was introduced and NZ became one of seven countries to have eradicated the disease.
"One of the great things in New Zealand is because there was mass immunisation at one point in the late 90s, it has continued through NZ and eliminated endemic measles," Hayman said. "So all the cases that we're seeing now have originated in other countries."
Hayman said the benefits of vaccinating far outweigh the negatives.
"There's really no correlation between people being immunised and developing autism and that's been very clear. It's probably one of the most studied things - on earth actually."
As the Director of Infectious Disease Research at Massey University, Hayman studies the ecology of diseases and world-wide population health. He says there's a social responsibility to vaccinate.
"If you vaccinate your child you are also protecting people in your community who can't be vaccinated, so there are some kids and people who can't be immunised because of an underlying medical problem.
"By you immunising, you are preventing those children from ever being sick.
"New Zealand is doing a really good job with the young children now. Actually what's interesting is it's older kids in early university and school-age who actually haven't ever had either of the vaccines."
But recent studies have shown non-vaccination has meant New Zealand has become vulnerable to measles outbreaks, like recently in Christchurch.
"One of the great things about immunising children against childhood infectious diseases, for example, is that you reduce the chance that they get sick from secondary infections. And that reduces the need for things like antibiotic use.
"And there's really good evidence to show that if you immunise children for measles, those children are also protected from other childhood infectious diseases because their immune system is actually stronger, they haven't been suppressed because they've been unwell from measles.
"So there's really good evidence to show immunising has these other indirect effects on healthcare systems and human population health."
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