NSW Health authorities are investigating another possible instance of COVID-19 spreading among returned travellers in hotel quarantine.

NSW Health 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.

All three cases arrived in Sydney on the same flight from Doha on June 1, and stayed in adjacent rooms in the quarantine hotel in Sydney’s CBD.

Genomic sequencing has shown all three cases have identical viral sequences of the UK variant, also known as the Alpha strain, of the virus.

⚠️PUBLIC HEALTH ALERT: NSW HEALTH INVESTIGATING SOURCE OF #COVID19 CASE⚠️ pic.twitter.com/quLCsl8eS1

— NSW Health (@NSWHealth) June 15, 2021

The couple tested positive on a routine day two-test on June 3, while the other returned traveller tested negative on the same date but positive for COVID-19 when tested two days later.

All three were transferred from the quarantine hotel to special accommodation where they remain.

NSW Health says transmission may have occurred on the flight, on transport from the airport to the hotel, in the lobby of the hotel, or while in quarantine.

Authorities have now contacted other returned travellers who have since been discharged from level four of the same hotel and have asked them to isolate and get tested.

–ABC