NSW has a new local COVID case, a mystery infection in a man who has spent several days in the community before being diagnosed.

The man, who is in his 50s, is described as having been “very active” in Sydney’s inner-east in recent days.

His positive diagnosis was confirmed on Wednesday afternoon and he is thought to have been infectious since last Friday.

NSW Health is using venue QR codes to trace the man’s movements while he was infectious.

Among the venues of concern is the busy Event Cinema at Bondi Junction, along with a host of restaurants and retailers. Health authorities want anyone who was at the cinema from 6-8pm last Friday to get tested for COVID.

Tweet from @NSWHealth

“This person did everything right, but it goes to show that we can’t take a single thing for granted,” Premier Gladys Berejiklian said.

“It goes to show we have to maintain our social distancing, have to make sure we have good hand hygiene, we need to get tested with the mildest of symptoms, and very importantly and significantly, we need to use QR codes.”

The man has not yet received a COVID-19 vaccine.

“We have to assume there’s other cases and our response will be proportionate as it always has been in NSW,” she said.

“Everybody in the state needs to be on high alert.”

The infected man has not returned from overseas, and does not work in hotel quarantine. Health authorities say the source of his infection remains a mystery.

“Genomic testing will give us some indication as to the strain and, therefore, some potential links,” Ms Berejiklian said.

Results of the genomic testing – which will include looking at strains of the virus circulating in NSW hotel quarantine and interstate – are expected on Thursday morning.

NSW chief health officer Kerry Chant said the man’s close contacts were also being tested and were isolating.

Dr Chant said she did not believe the man was infectious at his workplace and her main focus was whether he had passed the virus onto his household contacts.

“Understating the source will be really important to understand how many cycles we have seen in the community that we haven’t recognised yet,” she said.

Authorities were keeping an open mind while working to find the source of the man’s infection, she said.

They also expect more cases to emerge after the man’s mystery diagnosis.

Ms Berejiklian said it was too soon to say if the latest case would spark a return to tougher rules in NSW, but “all options are on the table”.

“We have to assume there’s other cases, and our response will be proportionate as it always has in NSW,” she said.

“No doubt this positive case will alert more people to come forward and get tested, and that’s a good thing.”

Ms Berejiklian also encouraged all eligible people to get vaccinated.

From Monday, people 50 and older have been able to get immunised at some Commonwealth-run respiratory clinics across Sydney.

Federal Health Minister Greg Hunt said on Wednesday: “We know the strength of the NSW system, the absolute global gold standard.”

-with AAP