The mumps outbreak is an epidemic, say Auckland health leaders, who have asked the Ministry of Health to launch a nationwide vaccination campaign.
The public health officials say the low immunisation rates are also leaving the city vulnerable to a potentially deadly, large scale measles outbreak.
They said they were now dealing with an epidemic because the disease can't be contained.
More than 1000 people have contracted mumps in Auckland this year, most of them from the so called "lost generation" of 11-29 year olds with low rates of measles, mumps, rubella (MMR) vaccination.
The chief executives of Auckland, Counties Manukau and Waitemata district health boards, and two senior Auckland Regional Public Health service officials, wrote to the ministry saying a national response was needed to help slow the disease.
Current measures were having little impact, their letter said.
It asked for a "catch-up" campaign for all those who haven't been vaccinated - most of them adolescents and adults.
That was crucial to bringing the outbreak under control and prevent it taking hold nationally, the letter said.
Mumps cases have already been reported in Dunedin, Whanganui, Northland and Hamilton.
In a statement to RNZ, Auckland Regional Public Health Service director Julia Peters said the outbreak could now be described as an epidemic because it was widespread and it was not possible to stop its transmission.
The outbreak was likely to continue for two years but with a nationwide vaccination programme the number of cases could be cut by a third, she said.
About 1.3 million New Zealanders are aged 10 to 29 and if the estimate that 40 percent are not fully vaccinated is correct, that would mean 570,000 are susceptible to mumps.
The Ministry of Health said in a statement it would give a response to the DHBs shortly.