A Hamilton City Councillor who wore an anti-vaccine t-shirt to an autism awareness event says she didn't mean to cause offence.

But Siggi Henry, known for her strident anti-fluoride stance, is defending her anti-vaccination views, saying many parents are too accepting of medical advice.

About 350 people attended the Light Up The Lake fundraising walk around Hamilton Lake on Friday - including Hamilton Mayor Andrew King.

The event was part of World Autism Awareness Day.

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City councillor and media personality Mark Bunting helped run the event and said Henry's t-shirt had left some families upset.

CHRISTEL YARDLEY/STUFF Mark Bunting helped run the Light up the Lake event in Hamilton (file photo).

The t-shirt read Vaxxed: From Cover-Up to Catastrophe, a reference to the pseudo-documentary of the same name. The film is based on comprehensively debunked research linking the measles, mumps and rubella vaccine (MMR) and autism.

"I was uncomfortable with Siggi's t-shirt because I saw the discomfort from the organisers and the families," Bunting said.

"I think what made me uncomfortable was the fact she wore the t-shirt as well as her councillor badge. I was at the event as the MC rather than as a councillor and so I didn't want to get into a good ol' debate with her in front of everybody.

"There were families there that were pretty upset by it."

The country is currently experiencing a measles outbreak with 37 confirmed cases in Canterbury. In Auckland there are 10 confirmed cases and a further 62 non-immune people in quarantine.

The outbreak is considered serious enough that medical researcher Sir David Skegg has suggested unvaccinated children in Canterbury should stay away from school because of it.

Henry expected her Vaxxed t-shirt to spark debate but didn't intend to cause offence.

In hindsight, her attire was inappropriate, she said.

The incident is not the first time the one-term councillor has courted controversy.

In 2016, Henry encouraged Waikato District Health Board members and fellow councillors to take up the anti-fluoride cause, saying health experts and "smarty pants" scientists had brainwashed the public over fluoride.

She also argued ratepayers shouldn't have to pay for council staffers to get the flu-jab and said fat people were a health hazard because they could fall on others.

"All I want is for people to do their own research and not take everything at face value," Henry said of her decision to wear the Vaxxed t-shirt.

"I wanted to get people talking but I didn't want to make them feel uncomfortable. Maybe I didn't think, I apologise for that."

A new Danish study has found that the MMR vaccination does not trigger or increase the risk of autism in children. The survey looked at more than half a million children born between 1999 and 2010 and is the single largest study on this topic to date.

Henry said she hadn't heard of the study but later contacted Stuff to say she had read the study and that her views on the MMR vaccine hadn't changed.

Henry uses a variety of Facebook groups to keep her informed on vaccines.

She bought the Vaxxed t-shirt following a showing of the pseudo-documentary in Hamilton in 2017.

CHRISTEL YARDLEY/STUFF Hamilton Mayor Andrew King said Siggi Henry's decision to wear a Vaxxed t-shirt to an autism awareness event was a "slap in the face" given the current outbreak of measles (file photo).

King said Henry's views didn't reflect any council stance. Her decision to wear the Vaxxed t-shirt along with her councillor badge didn't breach any code of conduct, he said.

"Personally, I trust the advice of medical people and scientists. I think the t-shirt is a bit of a slap in the face in regard to the situation that we have right now down in Christchurch with the measles outbreak and our experts trying to protect our children," King said.