Travellers from Victoria are being subjected to mass screenings at Sydney's major transport hubs as the NSW government continues to warn residents of a Sydney suburb to be on alert after a supermarket worker tested positive to coronavirus.
The man had been in hotel quarantine in Victoria from June 11 to June 26 after flying in from Bangladesh and tested positive to COVID-19 on the fourth day of his quarantine period.
He then flew from Melbourne on June 26 and returned to work at the Woolworths in Balmain on June 27, with his employer noticing he had minor symptoms.
NSW Chief Health Officer Dr Kerry Chant says the level of virus detected in the man is low but authorities are treating him as infectious as a precaution.
He worked at the store on June 27 and 28, and 50 employees are now in isolation after being identified as close contacts, with the store undergoing a deep clean.
Dr Chant says the man was assessed as non-infectious and cleared of the virus before he was discharged from Melbourne quarantine on June 26.
NSW Health Minister Brad Hazzard says anyone who visited the Woolworths store on either of the two days should come forward and be tested if they have respiratory symptoms.
Health authorities are also contacting people who sat around the man on Jetstar Flight JQ510 from Melbourne to Sydney on June 26.
The state's confirmed COVID-19 cases stand at 3211 after no new cases were reported in NSW on Friday, with one patient currently in intensive care.
"It's a very good day for a health minister when you can say we had absolutely no new cases," Mr Hazzard said on Friday.
But a school on the NSW Central Coast, Green Point Christian College, has been closed after being informed of a possible COVID-19 case in a senior male student, who will have additional tests.
Mr Hazzard also reiterated his plea for Victorians from hot spot areas to not enter NSW.
"If you're from the hot spots you shouldn't be leaving, don't defy your own government's laws," he said.
The health minister called on the Victorian government to screen passengers at train stations in the southern state to stop people from those areas from leaving.
Health authorities in NSW are screening people at airports and transport hubs across the state to ensure Melbourne residents from COVID-19 outbreak hotspots are not entering the state, and cars with Victorian number plates may be stopped.
Any who try to enter NSW could face six months' imprisonment or a fine of $11,000.
Victoria on Friday reported 66 new COVID-19 cases.
A woman this week who caught the train from Melbourne to Sydney despite having respiratory symptoms and waiting on COVID-19 test results is yet to have her results confirmed.
Meanwhile, NSW Customer Service Minister Victor Dominello on Friday said about 70 per cent of businesses have proven to be COVID-compliant and urged those who aren't to step up their game.
"There are businesses out there that pretend or believe that they live in a pre-COVID world - they need to wake up," Mr Dominello told reporters.