Three Perth children caught measles this week after they had contact with an non-vaccinated child in Rockingham.
The WA Department of Health released the information in its weekly virus watch report.
The three children, two of whom are babies, were exposed to the virus at Rockingham Hospital where the child of a non-vaccinating family was being treated for measles, reported The Weekend Courier.
It's understood the non-vaccinated child caught the virus in Bali.
According to a state government report released last year, most of the Perth metropolitan area fell below the current national average of 91.3 per cent for fully vaccinated two-year-olds.
Cottesloe, Claremont, Fremantle and Mundaring were reported as having some of the lowest vaccination rates for children under five years old while regionally, Augusta, Margaret River, Busselton and Manjimup were also behind the state average.
However, the number of expectant mothers receiving whooping cough vaccinations in WA has risen to 70 per cent, following the introduction of a free booster program established after the death of newborn baby, Riley Hughes, from the preventable disease in 2015.