Another 37 measles cases have been confirmed in Auckland overnight, prompting warnings by a health expert that the city is facing an epidemic.
The number of measles cases are spreading rapidly across the city with the total number of cases in Auckland this year now sitting at 546, according to the Auckland Regional Public Health Service.
ARPHS public medicine specialist Dr Maria Poynter said at over 500 cases it was a "very serious outbreak".
She urged anyone aged between 1 and 50 years old to make sure they had at least one measles vaccination as the ARPHS tried to stop it spreading.
Children under the age of 4 are the most affected, followed by people aged 15 to 29.
Just under half, 42 per cent, of people with measles this year have been hospitalised.
Nationally, 639 measles cases for the year so far had been recorded at the end of last week.
Of the cases confirmed today, 34 were in South Auckland, followed by 2 in Franklin and 1 in East Auckland.
In Auckland almost a third of the cases - 163 - have occurred in the last eight days and the majority have been in South Auckland.
Dr Nikki Turner, GP and director of the Immunisation Advisory Centre (Imac) at the University of Auckland, said the city was now facing an epidemic.
Turner said vaccination was the key to making sure people didn't contract measles.
The country's formerly poor immunisation rates meant a large number of teens and young adults were unaware they were at risk, she said.
The outbreak is placing a huge burden on Middlemore and Starship which are already swamped dealing with winter illnesses.
*An earlier version of this story reported there were 42 new cases overnight. This has been corrected following revised information from ARPHS.
What are the symptoms of measles:
• Measles symptoms include a high fever, runny nose, cough and sore red eyes.
• A few days later a rash starts on the face and neck, and then spreads to the rest of the body.
• Measles can spread before any symptoms start to show.