More cases of mumps have been reported this year in Auckland than in the past 16 years combined.
The Auckland Regional Public Health Service had been notified of 300 cases of mumps from January 1 to September 4 this year.
"Mumps is now at large in the community and the only way we can stop this spreading further is to achieve high levels of MMR vaccination in the population," Medical Officer of Health Dr Josephine Herman said.
She said the large number of mumps cases meant a large number of people were also at risk of contracting measles and rubella.
"The implications for young adults are deeply concerning, given the risk of non-immune pregnant women catching rubella. This can result in miscarriage or still birth and babies developing severe birth defects," Herman said.