Public health officials are warning passengers on two Air New Zealand flights or people who passed through Auckland and Wellington airports a week ago to check they are immunised against measles.

Photo: Sherry Yates/123RF

A passenger who did not know they had measles flew from Samoa to Auckland early on Saturday 7 December, then took a 5pm flight to Wellington.

Officials say other passengers on the flights, at the Auckland international or domestic airports or the Wellington domestic terminal, should watch for signs of measles.

It said it takes one to two weeks for symptoms to occur.

"You are most at risk if you're not immune to measles, either because you haven't been vaccinated or you haven't had the disease previously. People who are not immune may start experiencing symptoms over the next week," Medical Officer of Health at Regional Public Health, Dr Annette Nesdale said in a statement.

The flights in question are:

Air New Zealand flight NZ959; Apia to Auckland. Departing Apia on 6 December at 10.17pm and arriving in Auckland at 1.20am on Saturday 7 December

Air New Zealand flight NZ445; Auckland to Wellington. Departing Auckland at 5.00pm and arriving in Wellington at 6.23pm on Saturday 7 December

Meanwhile, a baby who was infected with measles has been discharged from Hawke's Bay Hospital.

However, health officials do not yet know where the infant contracted the virus.

They say the baby was too young for vaccination.

All the baby's family and close contacts have been tracked and traced to minimise the risk of any spread.

There have been 18 confirmed measles case in Hawke's Bay region this year.

So far this year, 2161 cases of measles have been notified in New Zealand - 80 percent of them in Auckland.