Parents need to immunise their children against measles or risk having them sent home from school for two weeks if there is an outbreak, the Ministry of Health has warned.
The ministry says the number of notified measles cases so far this year is already seven times the total number in 2008.
In Canterbury, there have been more than 100 cases, with 11 people hospitalised. There are 18 reported cases in the Auckland region.
Health official Dr Julia Peters says Auckland region's low rates of immunisation mean there is a rise in people, not just young children, becoming ill.
The ministry is asking doctors to recall all children aged between 12 months and 12 years who have not received a dose of the MMR vaccine.
Chief adviser of child and youth health Pat Tuohy says it is possible outbreaks can be managed and the ministry may not have to consider declaring an epidemic.
However, to control the outbreaks, Dr Tuohy says children who have not been immunised will be isolated if they have contact with an infected person.
Incentives to immunise advocated
The Ministry of Health says offering parents incentives to immunise their children is one way of improving patchy immunisation rates.
Dr Tuohy told a health select committee at Parliament immunisation rates in New Zealand are still poor by world standards and inadequate to prevent epidemics of preventable diseases such as measles and whooping cough.
Dr Tuohy says while some district health boards have come close to achieving a 95% immunisation rate, it is unlikely this will happen across the entire country under the current system.
He says in Australia, parents have to make a decision about whether or not to immunise their child at preschool age in order to receive funding.