NSW Health is investigating potential transmission of COVID-19 between returned travellers.
Routine genomic testing undertaken after the returned travellers tested positive now shows they share the same viral sequence for the B1.351 variant of concern, first identified in South Africa.
NSW Health is investigating the nature of transmission between the returned travellers, who entered Australia on 3 April on the same flight and subsequently stayed in adjacent rooms at the Mercure Hotel on George Street in Sydney's CBD.
All three people, two of whom are members of the same family, tested negative on their day-two swabs in hotel quarantine, before subsequently testing positive for COVID-19 later during their quarantine periods.
The two family members stayed in connecting rooms on the 10th floor of the hotel, while the third person was in an adjacent room. The family members tested positive on days seven and 10 of their stay, while the person in an adjacent room tested positive on day 12.
They have been transferred to the Special Health Accommodation, where they will remain until no longer infectious.
NSW Health is now urgently contacting returned travellers who had been staying on the same floor of the Mercure during what is believed to be the infectious period, 7 to 12 April, but have since been released from hotel quarantine.
They are being directed to get tested and self-isolate until 14 days from the day they left quarantine at the Mercure Hotel. Hotel staff who worked on the 10th floor at the Mercure are also being tested and self-isolating.
NSW Health urges everyone in NSW with even the mildest symptoms, such as headache, fatigue, cough, sore throat or runny nose, to come forward immediately for testing, then isolate until they receive a negative result.
There are more than 300 COVID-19 testing locations across NSW, many of which are open seven days a week.
To find your nearest clinic, visit Covid-19 testing clinics or contact your GP.