An Auckland mother has invited other parents to bring their kids over so they can catch chickenpox from her sick two-year-old, worrying medical experts.
She posted the invitation for a "chickenpox party" on a Facebook page for controversial anti-vaccination movie Vaxxed.
"My 2yr old has chickenpox currently if anyone that hasn't had it wants LIFETIME NATURAL IMMUNITY!!" she wrote.
The post attracted wide support from other members of the page, called Bring Vaxxed to Australia/New Zealand.
But it's horrified doctors, including Nikki Turner of the Immunisation Advisory Centre, who said it was "unethical" considering there's a safe vaccine available for chickenpox.
"Before we had vaccinations, we all used to do chickenpox parties because chickenpox is worse when you're older - without vaccinations, it's not an unreasonable decision," Dr Turner told Newshub.
"But when you've got a safe vaccination, this is just a lack of knowledge."
Of most concern was a person in Australia asking if a "swab" of the disease could be mailed to Australia.
"What a dreadful thing to do. That's so unethical," said Dr Turner.
"Putting a live virus in the post - are they not thinking of the safety of other people? This is on the edge of bio-terrorism."
- Dr Lance O'Sullivan storms stage at anti-vaccine film screening
- Pro-vaxxer's child threatened by anti-vaxxers
- Jesse Mulligan goes on rant against anti-vaccine advocates
Dr Turner says while the vast majority of kids survive chickenpox without any lasting ill-effects, there are several hundred hospitalisations and one or two deaths every year. Complications include skin infections, scarring, inflammation of the joints, inflammation of the brain, encephalitis, meningitis, pneumonia and bronchiolitis.
Chickenpox myths and realities
Responses to the chickenpox party's invite also included false information and common misconceptions about the virus.
"Adults should get re-exposed too as it may help prevent shingles later in life," wrote one person.
Totally wrong, says Dr Turner.
"Once you've had chickenpox, you've got the risk of shingles for the rest of your life. The virus lives inside you forever more... Re-exposure has got nothing to do with shingles."
Another respondent said having real chickenpox, instead of the vaccine, gives "lifetime immunity".
Also wrong. Dr Turner says while it's unusual, it is possible to get chickenpox more than once - but the second time is usually less severe, since the body has some immunity.
"Sometimes people misdiagnose shingles and think it's a second episode of chickenpox."
The mother's two-year-old thankfully appears to have made it through okay, his mother posting on Thursday night she was "pleasantly surprised" to say he was back to normal - aside from a "scabby body".
She didn't respond to Newshub's request for comment.
From July 1, the chickenpox vaccine has been available for all kids when they turn 15 months of age, and 11-year-olds who have either never had the vaccine or the disease.
It's also available free of charge for any child of any age that's deemed at high-risk, or at a cost of about $80.
Vaxxed, directed by disgraced former doctor Andrew Wakefield, screened in New Zealand earlier this year. One screening was sensationally gatecrashed by Northland doctor Lance O'Sullivan, who told viewers the movie would "cause babies to die".