All up 62 people were being contacted, although Dr Bell could not say how many of them were the aeroplane passengers.
He declined to elaborate on the staff member's role or the ward she worked in.
Before she realised she was ill there had been "countless opportunities'' for people to have been exposed, he said.
She had had contact in a clinical setting with the Cumberland College resident who became infected with measles last month. That infection was attributed to a Wellington student who visited the hostel in September, and later became ill.
New Zealand is experiencing a measles outbreak, mainly in Auckland.
As of October 27 there were 373 cases this year, 295 of them in Auckland.
Adults born before 1969 were presumed to have natural immunity from the highly infectious disease. People born from 1969 onwards should check they had had two doses of vaccine, he said.
Parents should ensure their children were vaccinated, for measles, mumps and rubella, at 15 months and 4 years.
"If there is a community outbreak, there may be a recommendation for these childhood vaccinations to be moved forward,'' he said.
* Measles facts box:
- Begins with fever, tiredness, a cough, runny nose, and inflamed red eyes.
- Incubation period can be up to 18 days.
- People with symptoms should stay away at home, and phone their doctor for help.
