The head of Starship Children's Hospital is warning some kids are likely to die from complications caused by measles.
In an open letter published in the Herald on Sunday, Dr Mike Shepherd details the serious harm measles is causing.
He says the hospital is seeing critically unwell children with things like pneumonia and brain infection caused by the illness, and he's extremely concerned.
"Some children are likely to die because of complications due to measles... Measles can be very dangerous. While many adults who get measles will have an illness somewhat like the flu, however one in 20 children will get serious pneumonia and around one child in 300 will get a life-threatening illness or die.
"We don't have a treatment for measles - once you or your child get sick with measles, the illness has to run its course. We can only help by treating complications, which can be life-threatening."
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He's pleading for people to get vaccinated - and to ensure other whanau are too.
"Remember the first symptoms are not a rash, they are cough, runny nose, and bloodshot and watery eyes and feeling unwell. If you are taking someone with possible measles to the doctor, please call ahead.
"Please help. Measles should be a story of the past, not something threatening our children's lives."
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As of Friday afternoon there had been more than 750 confirmed cases in Auckland. There are fears a large school sports tournament in south Auckland this upcoming week could see hundreds more infected.
Measles has been on the rise worldwide in recent years.
"There's so much measles globally at the moment it's probably happening on a daily basis, and it's going to continue to happen," vaccine specialist Helen Petousis-Harris from the University of Auckland told Newshub last week.
"If you feel unwell, please don't just turn up [to the doctor]. It is important to call first, because measles is highly infectious and you could infect others in the waiting room," said Maria Poynter of the Auckland Regional Public Health Service.
The World Health Organization (WHO) recently named the anti-vaccination movement as one of the top 10 threats to global health.
More than 100,000 people died of measles in 2017, the WHO says, most of them pre-school children. Before a vaccine was available, millions used to die annually.