Victorian testing boss Jeroen Weimar has categorically denied the Victorian health department sent mixed messages to the family at the centre of a cluster in Melbourne's north.
A frustrated family member says the Department of Health and Human Services cleared the family to leave isolation on October 17.
Two days later, the family sent their Year 5 boy back to East Preston Islamic College while infectious.
It sparked the northern metropolitan outbreak which has infected 39 people across 11 households and delayed the unveiling of eased restrictions for Melbourne.
The family, which has asked not to be named, told The Age that DHHS did not explicitly warn the boy should stay isolated.
"As discussed, your family has met the Department of Health and Human Service's (sic) criteria to end isolation," reads the published email, dated October 17.
The premier said it was "wrong" to conclude the family of eight had been told it had been cleared to leave isolation.
"No such advice was provided in relation to the child who went to school," Mr Andrews told reporters on Monday.
Mr Weimar denied his team had got it wrong, and said they had been "explicitly clear" with every single member of their household.
"I saw those letters and we send them individually ... to named individuals," the DHHS testing commander said.
"There are eight (people) in that household and there is a chain of almost daily discussions, telephone calls, meetings with people to explain what is going on as part of that wraparound care that we provide.
"So I am not going to sit here and say we are not explicitly clear about what is happening with individual members of a household."
