Health officials fear the Bondi Covid cluster has spread 60km south after a childcare centre was forced to close following a visit from a positive case.
Little Zak's Academy at Narellan Vale, in Sydney's southwest, revealed late on Tuesday that a young girl with the virus visited the centre.
'It has come to our attention from the NSW Health Department and Liverpool Health that we have a confirmed Covid-19 case from one of our children in our centre that attended yesterday (Monday),' the centre said in an email sent to parents.
The infected girl was in room '2-3' between 9am and 5.15pm.
'The girl and her family are doing well and resting at home,' the centre said.
'By 6pm the centre was closed and our Covid action plan was put in place.
'All staff were personally called and notified within 60 minutes of that happening and all parents were notified within 90 minutes of that happening.'
Little Zak's Academy at Narellan Vale, in Sydney's southwest, revealed late on Tuesday that someone with the virus visited the centre
The childcare centre is currently closed while it undergoes a deep clean.
Meanwhile, thousands of NSW families' school holiday plans are in chaos with most states and New Zealand blocking travellers from much of Sydney.
Just two days before public schools break for two weeks, Queensland has followed Victoria and New Zealand by imposing bans on travellers from much of Sydney as NSW braces for more COVID-19 cases.
From 1am Thursday, the state will close its border to people from the City of Sydney and the Woollahra, Bayside, Canada Bay, Inner West, and Randwick local government areas. Waverley was already on the list.
'To keep Queenslanders safe, we will be following exactly what Victoria has announced last night,' Premier Annastacia Palaszczuk said on Wednesday.
'This advice may have to be updated during the course of the day or into the evening.
'NSW is treating this seriously and we are treating it seriously.'
Other Australian states have imposed border restrictions for people from the hotspot areas, with Victoria on Tuesday declared seven Sydney local government areas 'red zones'.
Earlier on Wednesday, NSW Health issued a health alert after a person infected with the virus flew from Sydney to New Zealand and back.
The alert was for passengers travelling on Qantas flight QF163 on Friday night to Wellington, and anyone who flew on Monday morning on Air New Zealand flight NZ247 from Wellington to Sydney.
Passengers on board those flights must contact NSW Health immediately, get tested and isolate for 14 days regardless of the result.
The scare comes after New Zealand health authorities closed the trans-Tasman bubble with NSW for at least 72 hours after the state recorded 10 new cases on Tuesday, lifting the so-called Bondi COVID-19 cluster to 21.