Queenslanders have been put on alert after NSW recorded a new local Covid case with no known link to other infections.

NSW Health revealed on Wednesday a man in his 50s from Sydney's eastern suburbs tested positive to the virus after visiting a spate of venues across the city.

Queensland Health have now ordered anyone in the Sunshine State who visited a Covid exposure site in NSW during the specified times to quarantine at home.

'NSW Health has already made it clear that anyone who has been to any of those venues, should be quarantining, and not getting on flights,' Queensland Chief Health Officer Jeannette Young said.

'We're working closely with NSW to get a better understanding of the risk associated with this case, so as an interim measure, we're mirroring NSW Health's advice.

'We'll continue to assess the situation as more information comes to hand over the next 24 hours.'

Queensland Health have also urged recent travellers from NSW to monitor for coronavirus symptoms.

'If you have recently returned from NSW and not visited any listed exposure venues during the risk period, get tested if you have any Covid symptoms, no matter how mild, and isolate until you get the results and your symptoms resolve,' they said.

'Please continue to monitor the list of interstate exposure venues for 14 days after you arrive to ensure no new venues have been added.'

NSW Premier Gladys Berejiklian and Chief Health Officer Dr Kerry Chant said the infected man had a 'high viral load' and was potentially highly infectious while in the community.

He visited a busy Woolworths supermarket, several BBQ shops, a golf club, a cinema and many cafes and restaurants between Friday April 30 and Tuesday May 4.

'Our job now is to get on top of it to identify any other potential cases, to identify the source and make sure we get on top of this case,' Ms Berejiklian said.

There are now 19 'venues of concern' across the city from Double Bay in the east, to Collaroy in the north, and Silverwater in the west.

Dr Chant said the man had a higher viral load than typically seen in infected people, increasing the likelihood that he spread the disease to others.

More than 42,000 people in the inner west have also been put on high alert after virus fragments were found in wastewater from a sewage plant.

Affected suburbs include Marrickville Dulwich Hill, Summer Hill, Lewisham, Ashfield, Haberfield, Petersham, Lilyfield and Leichhardt.

NSW Health urged everyone in those areas to be especially vigilant in monitoring for symptoms, and if they appear get tested and isolate immediately until a negative result is received.

Experts said genome sequencing had begun and authorities were urgently notifying the man's close contacts and advising them to get tested and isolate - with one of his household contacts already testing negative.

Anyone who attended one of the following venues at the times specified is asked to immediately get tested and isolate until NSW Health provides further information.

District Brasserie, 2 Chifley Square in Sydney

Friday April 30, 11am - 11:45am

HineSight Optometrist, Sofitel Sydney Wentworth - P2/61-101 Philip Street in Sydney

Friday April 30, 12pm - 1pm

Barbetta, 2 Elizabeth Street in Paddington

Friday April 30, 1:30pm - 2:30pm

Friday April 30, 6pm – 8pm

Friday April 30, 8.45pm – 11pm

Saturday May 1, 1pm –1.45pm

Saturday May 1, 1pm – 1.45pm

Saturday May 1, 2pm – 3pm

Saturday May 1, 4pm – 5pm

Saturday May 1, 4.30pm – 5pm

Sunday May 2, 3pm – 4pm

The Stadium Club, Moore Park - Entertainment Quarter, 122 Lang Road

Monday May 3, 11.30am - 12.30pm

Azure Cafe, Moore Park - Entertainment Quarter, Shop 5a

Monday May 3, 12.30pm - 1pm

The Royal Sydney Golf Club, Kent Road, Rose Bay

Monday May 3, 12.30pm - 1pm

Rug Cleaning Repairs Hand Rug Wash Sydney, 8/52-54 Sydenham Rd, Brookvale

Monday May 3, 12.30pm - 1pm

Alfresco Emporium, 2021 Pittwater Rd, Collaroy

Tuesday May 4, 1pm - 1.30pm

Smith Made, 14/28 Roseberry Street, Balgowlah

Tuesday May 4, 2.30pm - 4pm

Chemist Warehouse, 459-463 New South Head Road, Double Bay

Tuesday May 4, 3.45pm - 4pm

Woolworths, Kiaora Lane and Kiaora Road, Double Bay

Tuesday May 4, 4.05pm - 4.15pm