Investigations to crack the mystery of patient zero in the northern beaches cluster are still underway

Investigations to find patient zero in the Avalon cluster are underway, with health authorities “not confident” where the infection came from.

NSW Health Minister Brad Hazzard says authorities are still “not confident” they know where the original case at the centre of the Avalon cluster came from.

Overnight, New South Wales had 30 cases of community transmission, 28 of which have already been directly linked to cluster that started in Avalon on Sydney’s northern beaches.

However, the source of the outbreak still remains a mystery, with Mr Hazzard referring to a “missing link” in the chain of infection, with the virus having passed through an unknown carrier before spreading to the beachside region.

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The northern beaches of Sydney have been ordered into a four-day lockdown until midnight Wednesday. Picture: NCA NewsWire/Bianca De Marchi

“The only missing link here at the moment is who was the original source of that overseas virus,” Mr Hazzard said at a press conference today.

“We have spoken about this before, there was one passenger who came in on December 1 and because of the incredible capacity of our pathology and tracing teams we know that the genomic sequencing has indicated that that person had a genomic sequence very close to the cases that were occurring in Avalon. But we don’t know how we got there, that is the issue.”

NSW chief health officer Dr Kerry Chant said finding the source of the northern beaches outbreak might be a “challenge beyond us”.

Dr Chant told reporters today an “intensive investigation” was underway into the outbreak. She said at this stage genomic sequencing suggests the outbreak came from a US traveller who was in hotel quarantine.

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The source of the Avalon cluster is believed to have been an infected traveller from the US. Picture: Getty Images.

“Can I just say, there is an intensive investigation under way and while I really do want to find the source, it may be that this is going to be a challenge beyond us,” Dr Chant said. “But we are doing everything we can.

“What we know is that this sequence from this strain that is associated with this cluster is most closely linked to a returned traveller from overseas who arrived in country on 1 December.”

Dr Chant said there was “no one else” who had been identified who could be the source of the outbreak, according to genomic sequencing.

“At the moment we are forensically looking at all of the journeys of that individual to see if there were any points associated with it.”

Dr Chant said contact tracers were also probing cleaners who may have been in contact with the room the traveller stayed in.

She said contact tracers were continuing to seek out possible cases from the Avalon gym, as they sought the “earliest possible case” and anyone who had been in contact with that individual.

“We have to keep an open mind because there may yet be an unknown source.”

Dr Kerry Chant said finding the source of the northern beaches outbreak might be a ‘challenge beyond us’. Picture: NCA NewsWire/Bianca De Marchi

NSW Premier Gladys Berejiklian announced today’s rise in COVID case numbers, along with a raft of restrictions to stop the spread.

Ms Berejiklian announced a 10-person limit on gatherings in people’s homes, for all of Greater Sydney, including the Blue Mountains and the Central Coast.

The Premier also announced hospitality, religious and other indoor venues would move back into a 4sq m rule across all of Greater Sydney. Venues had previously been allowed one person for every 2sq m of space in a venue.

A 300 person cap has also been introduced for all venues to assist contact tracers in the event of a superspreader event.