NSW Premier Gladys Berejiklian is urging young adults to rein in their social lives after a COVID-19-positive man attended a football match and six Newcastle pubs at the weekend.
It comes as NSW recorded 11 new coronavirus cases in the 24 hours to 8pm on Thursday, including one who attended The Apollo restaurant in Potts Point and eight who are close contacts of known cases.
One case, a female in her 60s from Sydney's southwest, is still under investigation while one new case acquired in Victoria is in self-isolation.
A man in his 20s, who was confirmed as a case on Thursday, attended several Newcastle venues between July 31 and August 2 including Bennett Hotel in Hamilton, Sydney Junction Hotel in Hamilton and the Wests New Lambton club.
NSW Health wants anyone who attended those venues between specific times to immediately self-isolate for 14 days from the day they attended and get tested.
The man also visited the Greenroof Bar and Restaurant in Hamilton, the Queens Wharf Hotel and Sushi Revolution in Hamilton, and was among 2570 spectators at the Newcastle Jets-Western United match on Sunday at McDonald Jones Stadium.
Anyone who visited those venues on those dates is considered a casual contact.
The man is a close contact of a Newcastle teenager whose diagnosis shut down his high school and sent two football teams into self-isolation.
"We are on a knife-edge and we are about halfway through what is a really critical period," Ms Berejiklian told Triple M radio on Thursday.
"To the young people, try and modify the number of places that you go to."
NSW Health on Friday said a household contact of a previously reported case attended St Francis Xavier's College in Hamilton East on August 3, 4 and 5. The school is closed for cleaning.
Other previously confirmed cases - two Sydney men in their 20s - attended several venues while potentially infectious.
One dined the Jambo Jambo African restaurant in Glebe on July 31 from 7pm to 8.30pm and anyone who attended the restaurant at that time should self-isolate and get tested.
The man also visited several other inner-Sydney venues between Friday and Sunday but patrons at these places are classified as casual contacts.
The other attended Penrith Plaza, Master Hot Pot in Canley Vale and BBQ City Buffet in Bankstown on August 1, and those who were at those venues should be alert for symptoms.
The Australian Medical Association, meanwhile, is encouraging NSW residents to wear a mask in public at all times despite current NSW government guidelines.
The NSW government recommends mask use where social distancing is impossible, as well as for public-facing employees, religious worshippers and those who live near COVID-19 clusters.
The elderly and those at high health risk should also wear masks.
"The government has been asking the community to do the right thing and while many people have responded, infections persist and NSW is struggling to return to the previous environment where it had no community transmission," AMA NSW president Dr Danielle McMullen said in a statement on Friday.
Australian Associated Press