Victorian authorities are investigating an apparent transmission of the coronavirus between residents of a Melbourne quarantine hotel.

It is understood genetic tracing revealed two guests on the same floor at the hotel have somehow transmitted the same British variant of the virus between the groups.

“That means it’s as if they have been in the same room together,” Victoria’s Police Minister Lisa Neville said on Wednesday.

“This is a hotel transmission, it is not a community transmission. The public health team … have indicated there is an exceptionally low risk of any community transmission.”

The manner in which the virus was likely transmitted points to how infectious the strain is.

“What the public health team believe is the … viral load in the room of the family of five … was so high that just even opening the door to pick up your food has seen the virus get into the corridor.

“The only reason that people open doors – there’s no interaction with staff – is to pick up their food or drop their old laundry out … because no one can enter their room.”

COVID Quarantine Victoria said late on Wednesday afternoon it was investigating how two separate resident groups at Melbourne’s Park Royal Hotel returned positive tests for the same strain of the highly infectious B117 variant first detected in Britain.

“Environmental testing and deep cleaning are underway and all positive cases were moved to a health hotel, where they remain in isolation,” it said in a statement.

“All staff are tested daily, and to date no staff have tested positive. Staff will undergo further testing and quarantine at home until further notice as an additional precaution.

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Ms Neville was at pains to point out there has been no community transmission.

The state’s Deputy Chief Health Officer Professor Melanie Van Twest echoed Ms Neville’s sentiments, noting the risk to the public of the recent case of the transmission of the virulent British strain of the virus in Victorian hotel quarantine was “extremely low”.

“At the moment we don’t believe there is any risk to the public, or at least that that risk is extremely low,” Professor Twest said.

“The infection is between two rooms of people who are already in quarantine. And who remain in isolation now at The Alfred health hotel.

“There is no indication at this point that other people on that floor are involved, or that staff members are involved, but we’ll know more about that tomorrow when we get the results of the testing that’s being done today.”

CQV said it was investigating how the two cases might be linked, including reviewing CCTV footage and testing the hotel’s ventilation systems.

“At this stage we don’t believe the residents have breached any infection prevention and control measures, or had contact with staff,” it said.

No staff members have yet tested positive. But about 100 have been sent home and tested again.

News of the quarantine scare broke on Thursday afternoon as Victoria reached 28 days without any new local cases of COVID – widely regarded as the milestone for community elimination of the virus.

On Wednesday morning, there were 21 active cases of the virus in Victoria, all in hotel quarantine.

–with AAP