Nearly half of those affected by measles in Auckland are under the age of five

That's why Public health officials have lowered the minimum age for the MMR shot, encouraging parents to take their kids for a jab from their first birthday instead of at 15 months.

Auckland Regional Public Health Service clinical director Dr Julia Peters says 43 percent of cases in Auckland have been for children under the age of five.

And she says they're particularly seeing an impact in children under two years of age.