Almost 200 additional mothers and babies will need to receive extra vaccines after they were given potentially ineffective doses due to fridges running at the wrong temperature at a Sydney hospital.
Bankstown-Lidcombe Hospital is in the process of contacting 91 women who will need an additional Boostrix vaccination.
Another 91 mothers are being advised their babies may have received a less effective hepatitis B vaccine.
"We want to reassure all involved that potentially less effective vaccine is not harmful," South Western Sydney Local Health District spokesman Dr Stephen Conaty said in a statement on Monday.
Some 282 mothers had previously been told from late January that their babies might have been affected by the bungle.
A SWSLHD investigation into the mishap said overcrowding in the hospital's fridges was behind three separate so-called "cold chain breaches".
"The cause of the periods of low temperature cycling of the fridge were almost certainly due to stock crowding the in-built temperature sensor at the right hand base of the fridge," a report released on Monday states.
The crowding impeded cold air reaching the sensor and created a small pocket of relatively warm air which then caused the fridge compressor to turn on.
This lowered the temperature in the remainder of the fridge below the recommended 2C to 8C range.
The report also found temperatures were recorded daily rather than twice daily as is standard, the relevant policy didn't stipulate a frequency for downloading temperature data logger information and cold chain breaches weren't escalated properly.
