Parents who choose not to immunise their kids are keeping it a secret from family and friends, rather than have to justify their controversial decision.
Edith Cowan University researchers interviewed a group of parents from an anti-vaccination cluster area about their reasons for not immunising their children.
All the parents said they hadn't told their extended family and friends that their children weren't vaccinated.
"They don't want the confrontation, they're tired of people questioning their choices, and they don't want to justify their decision, so they just don't tell people," researcher Bronwyn Harman said, noting it was a very polarising and emotive issue.
"This is a huge problem if Australia-wide we've got a group of people choosing not to vaccinate their children and they're not telling people. We need to stop vilifying these people so they are able to identify themselves so we don't put people who do choose to vaccinate at risk."
The anti-vaccination parents were very mistrustful of the government and doctors, suspecting that they were in the pocket of the pharmaceutical companies. "They [question] if they can believe everything they're being told," Dr Harman said. "They think the government in particular, and doctors, are trying to scare people into vaccinating their kids."
These parents consider the new "no jab, no pay" policy which will see taxpayer benefits withdrawn from families whose children aren't up to date with their immunisations, as another example of this manipulation.
They felt the media presented only one side of the issue, and anti-vaxxers were bullied on social media for being "bad parents". They said it was their right as parents to decide whether or not to vaccinate their child. "They felt personal responsibility to their own child, that they need to make the decision for their own child, they couldn't rely blindly on what the experts say," Dr Harman said.
The parents said they had researched the issue and believed the risks of childhood immunisation outweighed the benefits. They didn't cite concerns about a particular medical condition, but were simply unsure about the long-term health effects of vaccines. They believed that following a healthy lifestyle would protect them from disease.
Engadine mother-of-three Karen Bowness is in a quandary over the "no jab, no pay" policy. Her first two children have been fully vaccinated, but she abandoned the immunisation schedule for her third, son Taj, after he started showing signs of Asperger's Syndrome when he was three and she read the controversial - and since disproved - links between autism and some childhood vaccines.
"I would hate to put something in my son's body if he's got Asperger's and it's going to make it worse," Ms Bowness said. "How could I live for the rest of my life knowing I did that?"
She spoke to her GP who told her she could register as a conscientious objector, which she did. However, the government no longer considers this a "valid exemption category", so Ms Bowness could lose her family benefits if she doesn't get Taj, now 13, fully immunised.
"I [don't] want to be forced to put something foreign in my child's body that may cause him long-term damage," she said. "I think the government needs to allow for this type of informed decision."
Ms Bowness – whose family and friends know of, and understand her choice, defends it as her personal decision to do the best for her son. "I don't want to put other people's children at risk but I have the right to protect my child."
No jab, no play
As of January 1, 2016, parents won't be eligible for childcare subsidies and will lose Family Tax Benefit part A payment if their children aren't up to date with their vaccinations.
Children who aren't fully immunised can't be enrolled in NSW childcare centres unless they have a specified exemption.