NSW Health is investigating the source of a COVID-19 case diagnosed in hotel quarantine which has an identical viral sequence to two cases staying in an adjacent room.
The department said on Tuesday night it was unclear how and where transmission occurred from a couple to another returned traveller who were all staying on the fourth floor of the Radisson Blu quarantine hotel.
Genomic sequencing has shown all three cases have identical viral sequences of the Alpha strain (B.1.1.7).
The couple, who were asymptomatic, tested positive to COVID-19 on a routine Day 2 test on June 3, NSW Health said in a statement.
The other returned traveller returned a negative Day 2 test on June 3 before subsequently developing symptoms and testing positive for COVID-19 following a test on June 5.
The three cases were transferred from the Radisson Blu to the Special Health Accommodation, where they remain.
All three cases arrived into Sydney on the same flight from Doha on June 1 and stayed in adjacent rooms in the quarantine hotel.
“Early possibilities as to where transmission may have occurred from the couple to the secondary case include on the flight, on transport from the airport to the hotel, in the lobby of the hotel, or while in quarantine.”
NSW Health said there was no evidence of further transmission.
“Out of an abundance of caution, all returned travellers who were on the same floor of the Radisson Blu hotel between June 1 and June 5 and were subsequently discharged are being contacted and asked to get tested and isolate at home pending further advice from NSW Health.”
All staff who worked on the fourth floor of the hotel between June 1 and June 5 have been asked to get tested and isolate pending further advice.