A passenger who did not know they had the measles travelled on return flights between Auckland and Sydney less than two weeks ago.
Measles is an airborne disease that spreads easily through the air through coughing and sneezing. It can take seven to 14 days for symptoms to show.
New Zealand is in the grip of a measles outbreak, with over 800 confirmed cases in Auckland as of Monday, and almost 1,000 in total across the country.
The Auckland Regional Public Health Service had been notified of the outbreak today and issued a warning for other passengers on the flight.
The service confirmed it is the first instance of an infectious traveller flying between the countries during the current outbreak.
The New Zealand national travelled on Air New Zealand Flight NZ711 to Sydney just before 8pm on Friday 23 August. He returned to Auckland on Flight NZ108 which departed Sydney at around 7.50pm on Sunday 25 August.
“There is a serious risk of it spreading to anyone travelling on the same flight who is not vaccinated,” University of Sydney infectious disease expert Professor Ramon Shaban told SBS Dateline.
Professor Ramon Shaban said the news is concerning but notifications are routine.
“This is a perfect reminder that everybody should ensure they have their vaccinations up-to-date,” he said.
“If everybody on that flight was vaccinated, there would not be a significant concern.”
Medical Officer of Health Dr William Rainger said in a statement that people who may have been in contact with that person should be vigilant for symptoms of the highly infectious disease.
Symptoms include a high fever, runny nose, cough and sore red eyes.
"A few days later a rash starts on the face and neck, then spreads to the rest of the body," he said.
Vaccination with the Measles, Mumps, Rubella vaccine (MMR) offers the best protection against measles. One dose will prevent measles in 95 per cent of people, while having two doses will protect 99 per cent of people who have the vaccine.
Last week, the New Zealand Prime Minister Jacinda Ardern urged anyone not vaccinated to stay away from Auckland.
"The smartest, safest thing to do is to be vaccinated,” she said.
