Authorities are reviewing CCTV footage and conducting environmental testing at the Park Royal Hotel at Melbourne Airport, including a further review of ventilation systems to ensure the virus did not carry from one room to another.
A member of the family recalled opening the hotel room door - either to collect food or put out laundry - at the same time as someone in the room opposite opened their door. CCTV footage has not shown any occasion on which members of the two rooms exited their rooms simultaneously.
Ms Neville said the spread was not the product of breaches of protocols inside the hotel.