The incidence of pertussis or whooping cough is rising on the already hard-hit West Coast.
Since May there have been 250 notifications of suspected whooping cough, and in the past week the number of confirmed cases has risen from 110 to 130. Three people have been taken to hospital.
The West Coast Medical Officer of Health, Cheryl Brunton, says her area has New Zealand's worst incidence of the disease, but there have also been problems in Nelson-Marlborough, Canterbury and Hawke's Bay.
Dr Brunton says it is important for people to get vaccinated and to make sure boosters are taken, as immunity can wane.
She says the best protection is for babies and children to be vaccinated on time.