Outbreaks of measles in Otago, Canterbury and Auckland have prompted the Ministry of Health to buy 35,000 extra doses of the measles, mumps and rubella vaccine.
The ministry says it 10,000 doses of the MMR vaccine are normally used across the country every month, but more are needed after this year's outbreaks.
So far this year 149 cases have been confirmed nationwide. Health Minister Tony Ryall says that is more than ten times the number of people infected during the whole of 2008. He says the ministry is trying to source more MMR vaccine doses, in addition to those it has already secured.
Nearly 100 people have contracted measles in Canterbury alone since June and ten have been hospitalised.
The Canterbury District Health Board says the strain of measles in the area probably originates from south-east Asia and is not related to the cases in Otago, which began when a family returned from Vietnam earlier this year.
Virologist Dr Lance Jennings says measles is not endemic in New Zealand at present, but is introducted by infected people returning from overseas.
He says initial tests show the Canterbury strain has also been found in Singapore.
Maori children at higher risk
Maori parents are being warned their children are at particular risk of contracting measles.
South Auckland GP David Jansen told Waatea News measles can cause serious side-effects, and Maori in particular are more at risk in terms of spread of the illness because immunisation rates are lower and Maori probably have more social contacts.
Dr Jansen says many Maori appear unaware of the importance of vaccinating their children.