South Australian Premier Steven Marshall.
Photo: AFP / Brenton Edwards
An SA Health report into the transmission concluded "there was no high-risk single event or high-risk breach in infection prevention and control practices".
It found the transmission was "highly likely" caused by "the close timing of doors opening and closing between adjacent rooms".
The Melbourne man tested negative to Covid-19 while in hotel quarantine and flew back to Melbourne, where he tested positive six days later.
Victorian authorities have used genomic testing to link the man to the latest cluster in that state.
The report found that "a review of the timing and placement of food/goods/waste/linen outside of guest's rooms is likely to reduce the risk of further episodes of similar transmission events".