More than 100 cases of measles have been confirmed in Waikato during the latest outbreak, with the vast majority of patients not fully immunised, Waikato District Health board says.
Over the past two months 114 cases had been confirmed and only four of those were people who had been immunised.
Waikato DHB medical officer of Health Anita Bell said immunisation was the best protection from the potentially serious disease.
"Immunisation protects not only the individual, but also blocks the spread of this disease within our communities."
Unimmunised people who had been in contact with a person with measles, would normally be advised to stay at home and away from all public places, school or work for 14 days after their contact.
In over a third of the cases the disease was passed on to somebody in the household, who were already placed in quarantine before they became unwell, a DHB spokeswoman said.
About 80 per cent of cases were aged between 10 and 20. Of the others, 15 per cent were aged under 10 and 5 per cent over 30.
In nine cases measles sufferers were hospitalised but they were now well, the spokeswoman said.
Dr Bell said anyone born before 1969 or who had received two doses of the MMR vaccine could reasonably assume they were already immune.
If families suspected someone had measles they should call their doctor, where possible, before visiting to avoid spreading the disease while waiting. Measles was spread by tiny droplets in the air and was one of the few diseases that could spread so easily to those nearby.
Anyone showing symptoms of measles, which included fever, cough, blocked nose and sore red eyes, should immediately phone their doctor or Healthline on 0800 611 116 for advice, Dr Bell said.