New Zealanders are being warned our remote location is no longer a barrier from diseases.
Thirty-seven cases of the measles are now confirmed in Canterbury.
Polio New Zealand president Brian Robinson is urging people to get vaccinated.
"It's only a flight away now, any disease. There are so many migrant people coming in - one of them could be a carrier. And it could be someone from New Zealand who's travelled overseas."
Canterbury Medical Officer of Health Ramon Pink said on Thursday a wider group of people are now eligible for the vaccine, in order to control its spread.
In addition to those aged one to 28 who have never been vaccinated, caregivers of infants up to 12 months and people aged between 29 and 50 with children will now also be eligible.
"Our vaccination campaign over the next four weeks aims to target those still at risk of being infected by measles, or having serious complications from it," said Dr Pink. "We believe we have enough stock of the MMR vaccine to support our campaign."
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Robinson caught polio in 1949, and is now facing the long-term impacts. He says just because a disease has largely been eradicated from our shores, that doesn't mean we can ignore it.
'It's not there, we don't have to worry about it.' Well I'm sorry, you do. It's no use saying, 'Oh well, we could have done something to prevent it.'"
Robinson says if he was vaccinated in the 1940s, he wouldn't still be suffering today. The polio vaccine entered use in 1955.
"With measles, it's much the same thing - anyone who's not vaccinated, there's a good chance you're going to pick it up."
Measles is highly contagious. People are considered fully protected from measles if they have had two doses of the MMR vaccine, have had clinically confirmed measles or were born before 1969, when the disease was in widespread circulation.