A precautionary health alert has been issued for a Sydney cafe and venues in the Wollongong area after a returned traveller tested positive for COVID-19 following their 14-day quarantine period.
Shops, a cafe and a hotel are among the venues where those who visited at around the same time should get tested immediately and self-isolate, NSW Health said in a statement on Sunday night.
The person tested positive on the 16th day after arriving, having returned two negative tests during their 14-day quarantine period, the department said.
"Test results indicate that the person has a low level of infection and their household contacts have returned negative results to date.
"Investigations to date suggest the infection was likely acquired overseas and there is no indication at this stage that there was transmission in the hotel quarantine setting."
Close contacts of the case are in self-isolation and are not associated with the venues of concern, NSW Health said.
Meanwhile, Sydney businesses have been busted for not using the NSW government-mandated QR code app, more than a month after it became a legal requirement.
A restaurant at Canley Vale in the city's southwest was one of nine businesses fined as part of police compliance checks on Saturday night.
NSW Police said the most common breaches identified among all the venues were failing to sign customers in via the Services NSW QR code app and not completing a COVID-19 Safety Plan.
As of January 1, it was mandatory for hospitality venues and hairdressers in NSW to use the government's QR code system to electronically register customers to aid contact-tracing efforts.
The Canley Vale restaurant was issued a $5000 fine, while the other eight businesses were slapped with $1000 penalty notices.
Police are asking the public to dob in suspected breaches of any ministerial direction or behaviour that could jeopardise public health and safety.
NSW clocked up its third week of no locally acquired cases of coronavirus on Sunday.
A returned traveller in hotel quarantine was the only new infection detected among more than 9000 tests to 8pm on Saturday.
It comes as NSW introduces non-compulsory "day 16" testing for overseas travellers in a bid to pick up cases that might develop at the tail end of the 14-day incubation period.
South Australia said it would consider adopting NSW's approach, while Victoria is also encouraging released returned travellers to take the extra test.