On average, it can take up to two weeks from the day people were last in contact with someone with measles before they start showing symptoms.
A small number of people will still get measles up to three weeks after being exposed.
Dr Jackson said for the year to date, 42 per cent of those with measles lived in the Far North, 40 per cent in Whangārei and 18 per cent in Kaipara.
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Figures from the Institute of Environmental Science and Research (ESR) showed 1681 people had measles throughout New Zealand as at Friday last week, with 1370 in Auckland alone.
Dr Jackson is urging anyone who has been in contact with someone with measles to stay at home and away from other people for two weeks from the date they were last exposed.
"This is because people with measles are infectious for a few days before they get sick, and because the early signs of infection are very like the start of a cold or the flu."
If people have been exposed to measles and start to feel unwell, they are advised to call Healthline on 0800 611 116 for advice and information in the first instance.
Those needing to see a doctor should call ahead to their GP or the emergency department so they can prepare for their arrival.
Northland DHB clinics for 15 months, 4 years and up to 30-year-olds who have not had an MMR are being held at 22B Commerce St in Whangārei on Tuesdays and Thursdays between 8.30am and 4pm.
The other drop-in clinic is at the Kaitaia Hospital Whare on Thursdays from 12.45pm to 4pm.