Doctors are worried more WA parents are refusing to immunise their children, despite the overwhelming evidence about the benefits of vaccination.
The latest Australian Childhood Immunisation Register figures for the end of March show 4267 children under seven years old have been registered by parents with a conscientious objection to immunisation.
That equates to 1.79 per cent of the 238,384 children under seven in the State.
Two years ago, a conscientious objection had been recorded for 3366 children, or 1.5 per cent of the 224,386 under sevens.
WA has the third-highest rate of conscientious objection behind Queensland and South Australia. Nationally, 1.63 per cent of children have not been immunised because of their parents' objection.
Australian Medical Association WA president Richard Choong said though the number of objectors was small, it was still alarming.
"We've got 4500 children not protected and they place themselves at risk and they place people around them at risk," he said.
"Those parents are very committed to not having their children immunised but they have misguided and mistaken beliefs."
Dr Choong said about 90 per cent of WA children were immunised "but we should be getting much more than that".
The figures coincide with a push by grassroots WA Liberal Party members to close a loophole allowing conscientious objectors to continue to get welfare payments.
The previous Labor government introduced rules denying families the Family Tax Benefit Part A end-of-year supplement of $726 a child if their children were not fully immunised at age one, two and five.
But immunisation opponents registered as conscientious objectors are exempted.
The WA Liberal Party's State Council moved this month to quash the exemption, with the proposed policy to be debated next month by the party's Federal Council.
Federal Health Minister Peter Dutton said yesterday that stripping family payments was a "nuanced discussion" but one he was happy to have.
He said he was consulting Social Services Minister Kevin Andrews and Assistant Education Minister Sussan Ley, who oversees childcare policy, on what the Government would do to boost immunisation rates.
"It's an area of great interest to the coalition because we believe very strongly that Australian children should be vaccinated," Mr Dutton said.
"We are working on what our response might be by way of the next step because it is important to make sure that we can get herd immunity and make sure we can get greater coverage, particularly in some pockets where numbers have fallen away quite dramatically."
Dr Choong said methods such as withholding family payments did improve immunisation rates but a drawback was it did not affect families outside the welfare system.
_The West Australian _revealed last week that health officials were worried about a surge in measles cases and urged vaccination against the disease.