Royal Prince Alfred hospital in Sydney is contacting hundreds of women admitted to one of its postnatal wards between August 2013 and January 2015 after a fault was detected in a refrigerator containing routine vaccines.
Because of an issue with the thermostat in ward 8 East, the hospital said it could not guarantee the effectiveness of the measles, mumps and rubella combined vaccine, as well as diphtheria, tetanus and whooping cough vaccinations given to 570 new mothers as well as nine babies.
There was no risk to patients, the hospital said, as receiving potentially less effective vaccines is not harmful.
But patients may not be adequately immunised and, therefore, protected against the illnesses. The hospital is contacting all women affected as a precautionary measure.
A free clinic has been set up to provide re-vaccinations to women who may not have sufficient cover which will run until the end of the month at Croydon health centre.
All women who delivered a baby at the hospital during the period can contact a clinician on 1800 300 243.
In a statement, the hospital said it apologised for any inconvenience or concern caused.
A Sydney local health district spokesman said it was mostly women affected.
“However, we are contacting nine babies born to hepatitis-B positive mothers and who received that vaccine as a precaution,” he said.