Four of the wealthiest, healthiest suburbs of Melbourne have the worst child vaccination rates in the state, in part because of parents' complacency about the risks from infectious diseases.

In Burwood East, South Yarra, St Kilda and Brighton, about 85 per cent of children were vaccinated, eight percentage points below the nationwide figure.

And in each of these areas, the vaccination rate has dipped markedly compared with five years ago. Burwood East had the lowest rate of any Victorian postcode, with 85.3 per cent of children immunised, down from 94 per cent five years ago.

Although new Australian Institute of Health and Welfare data shows immunisation coverage for Australian five-year-olds has improved, a worrying trend continues in some inner-city areas.