The Northland doctor who stormed the stage at a screening of an anti-vaccination film says seeing his young daughter sick with a "high fever" and "body rash" was a pivotal moment in solidifying his pro-vaccination stance.
Dr Lance O'Sullivan, the 2014 New Zealander of the Year, spoke at a screening of Vaxxed in Kaitaia in May, telling the organisers "your presence here will cause babies to die", before performing a defiant haka.
He had been invited to the screening by the organisers, but said he had planned to attend regardless of whether he was welcome.
During his passionate speech, he said there is absolutely no evidence vaccines cause autism and he is concerned for his community because immunisation is safe and extremely important for children.
In an article by Dr O'Sullivan published by Fairfax media today Dr O'Sullivan says his daughter, Te Miringa, became unwell when she was under the age of two, with a "high fever and a body rash" during a measles outbreak.
A this point he and his wife decided to get Te Miringa immuniesd, after Dr O'Sullivan had previously read an anit-immunisation pamphlet at medical school.
It wasn't until Te Miringa was hospitalised a year later, that he realised getting her immunised was the "best decision."
Te Miringa was admitted to Starship Hospital with "peri orbital cellulitis", a severe eye infection which needed to be treated with a week of intravenous antibiotics.
"I remeber the doctors on the ward round asking if our child was immunised, because historically the most common cause for this potentially fatal condition (it can lead to brain infection and abscess and death) was Haemophilus Influenza."
"I recall their relief and ours when they advised us that the fact she was immunised had all but eliminated this killer condition from the list of culprits.
"I recall the pride when I could say that our child was fully immunised and as protected as possible, knowing that then, like now, that while we could not provide 100 per cent cover from every ailment, we had made the best decision."
Before he became a father, Dr O'Sullivan stumbled across an anti-immunisation pamphlet which was left behind in one of his lecture theatres which made him question his stance on immunisations.
"I read the pamphlet," Dr O'Sullivan says in his article.
"It described "studies" in the Netherlands into communities that didn't look like mine, but I took little persuasion.
"I stated our second child, our little daughter Te Miringa, would not be immunised."
When his daughter became ill, he "realised the information from the Netherlands did not reflect" his "reality".
Since his public pro-immunisation stance, Dr O'Sullivan has come under fire on social media, with people lashing out against the doctor by saying he was bought and paid for by a big pharmaceutical company.
The campaigners have also attacked his disabled son, who has muscular dystrophy.
Screenings of Vaxxed across the country, including Whangarei and Kaitaia, had been kept secret, with organising group WavesNZ notifying ticket holders of the venues just a few hours in advance.
The film is a 2016 American film from anti-vaccination activists Del Bigtree and Andrew Wakefield.
It was widely criticised by the scientific community upon its release, with various reviews saying it cherry-picked facts, relied on unsubstantiated claims and used emotional pleas and context-free statistics to get its message across.