Worries over children in Northland, where immunisation rates are low and more measles cases have appeared, to a total of six

One person is infected in Queenstown, but Health New Zealand has found no links between the two regions.

It's working out close contacts, and possible infection locations.

Auckland University vaccinologist Helen Petousis-Harris says child vaccination rates in Northland are the worst in the country.

She says this means the region's youngest children are at high risk of measles, and the complications that come with it.