Parents have told a national survey their unvaccinated children had been denied treatment because their shots were not up to date.

The findings come as one in 11 parents say they still believe vaccination is connected to autism and 30 per cent are unsure about this, despite extensive medical research showing no causal link.

"I'd be very disappointed if that is the case," said Australian Medical Association president Michael Gannon, in response to claims doctors could be among those refusing treatment. The nurses' union has also rejected that nurses would deny treatment.

"No matter what reservations an individual doctor might have, it's not ethical to deny care to an unvaccinated child," Dr Gannon said, stressing that refusing care to anyone, but particularly children, who don't get to choose their vaccination status, was unethical.

"Having said that, I understand individual doctors perhaps changing their practice based on the threat to their other patients. For example, if you have a child with measles, the last thing you want is them in your waiting room potentially infecting other children."

The findings are from the Melbourne Royal Children's Hospital Child Health Poll, which quizzed nearly 2000 parents of 3500 children in January, most of whom - 95 per cent - had fully immunised their children.

Just 1 per cent of children were completely unvaccinated and 6 per cent were selectively unvaccinated.

Federal Health Minister Greg Hunt has said he will refer the findings about care refusal claims to the health practitioners' watchdog.

"Whilst I absolutely urge all parents to vaccinate their children, I am concerned by this research and will be referring it to the Australian Health Practitioners Regulatory Agency for further investigation," he said.

The survey did not ask parents which type of health providers had refused treatment, and relied on accurate reporting by parents to a question that asks if their child was refused care because they were not fully vaccinated.

The poll's director, Dr Anthea Rhodes, said she believed the health practitioners would include doctors and nurses, particularly those who cared for children under six, as 25 per cent of younger children not fully vaccinated were reportedly denied.

"Those young children are attending regular maternal health nurse reviews. Alternatively, they may be attending their GP," said Dr Rhodes, who is also a practising paediatrician.

"All children have an equal right to access healthcare regardless of their vaccination status and this is a very worrying finding that suggests problematic practice here in Australia.

"These children are not choosing for themselves to be unvaccinated."

Paul Gilbert, Victorian assistant secretary of the Australian Nursing and Midwifery Federation, said ethical codes required nurses to provide "respectful and non-judgmental" care to all their patients

"At no time would they not see a child who hasn't been immunised, because it's another opportunity to engage with parents about why they should reconsider their choice," he said.

After several large outbreaks of vaccine preventable disease in the US, including measles, the American Academy of Pediatrics last year changed its position on refusing patients to allow paediatricians to do so, but only as a last resort.

This change in position was prompted by rising vaccination refusal rates and the frustration of clinicians.

The Australian poll has also revealed that three-quarters of parents want to be informed about the vaccination rates of schools and childcare centres and that most (70 per cent) would take this into account when choosing where to send their children.

Senator Pauline Hanson has tried to capitalise on vaccination fear, telling the ABC's Insiders program that the government should stop "blackmailing" parents by linking vaccination with welfare payments.

"What I don't like about it is the blackmailing that's happening with the government," she said.

"Don't do that to people. That's a dictatorship."

Victorian Health Minister Jill Hennessy, who introduced laws that ban unvaccinated children from kindergarten unless they have a medical reason, said the findings had demonstrated how irresponsible Ms Hanson's comments were.

"Refusing to treat an unvaccinated child only compounds the very serious health risks their parents are already exposing them to by not vaccinating them," she said.

Dr Rhodes said future research needed to explore who is refusing care, in what context and what consequences this has on families.