Three young children caught measles this week from an unvaccinated child, according to WA’s peak medical body.

The two babies and one child were exposed to the virus at Rockingham Hospital’s emergency department in mid-January, when a child of a non-vaccinating family presented with measles.

This was revealed in WA Heath’s virus watch for January 29.

The report also documented two cases of mumps in adults – one case was acquired locally and the other in Indonesia.

Only 89 per cent of Rockingham one-year-olds are fully vaccinated according to the Healthy Communities government register.

For two-year-olds the rate is 86 per cent and 87 per cent of five-year-olds.

Herd immunity against measles occurs when 90 to 95 per cent of the population is immune, especially through vaccination.