NSW Premier Gladys Berejiklian has confirmed there have been no further locally acquired COVID-19 cases after a security guard who worked at two Sydney quarantine hotels tested positive on Sunday.

Ms Berejiklian said more than 8000 people were tested on Sunday.

The Premier said she was concerned the security guard who worked at the Mantra Sydney Central and the Sofitel Wentworth had acquired the virus but not surprised.

“Pleasingly to date there is no evidence of widespread transmission but of course we know how dangerous the various strains of the virus can be so [NSW] Health is doing everything they can to make sure we stay on top of it,” she said.

Chief health officer Kerry Chant said genomic sequencing had revealed the man was a match with an infected traveller staying on the 11th floor of the Sofitel and both had acquired the more infectious British strain of the virus.

Dr Chant said it still wasn’t known how the security guard contracted the virus as the return traveller had not even opened their hotel door while the guard was on shift between 7pm on March 12 to 7am on March 13.

“This investigation has some uncertainties as to the exact mechanism of transmission and obviously I’d be a lot more comfortable if I knew that specifically so we are keeping our options open and exploring a range of possibilities,” Dr Chant said.

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The man’s co-workers at the Sofitel and Mantra must get tested as health authorities want to rule out the possibility that a colleague passed the virus on to the guard, Dr Chant said.

She said CCTV in the hotel showed the guard had demonstrated “exemplary” adherence to all health procedures while working and was wearing a face mask for the entire shift.

All travellers staying on the 11th floor of the Sofitel will be re-tested on Monday and must remain in quarantine until March 23.

The security guard had received his first dose of the Pfizer vaccine before becoming infected and Dr Chant said blood tests on Sunday showed his body had already had some response to the vaccine.

As well as working in the hotel quarantine program, the 47-year-old security guard worked in a building management role at the Highpoint Apartment Towers at Hurstville in Sydney’s south.

“But I would want to assure residents that this gentleman did not have any close or casual contact with any residents in that apartment complex,” Dr Chant said.

As the man was not symptomatic, he attended six venues while unknowingly infectious.

Only one venue, Pancakes on The Rocks in Beverley Hills, has identified close contacts though, with about 40 people (both customers and staff) needing to isolate for 14 days.

Health departments in Victoria, Western Australia, Northern Territory, South Australia and Tasmania have issued alerts in response to the new case in Sydney but Ms Berejiklian has pleaded for caution around any changes to border controls.

“I would urge all state governments to give us a chance to demonstrate out capacity to get on top of this,” she said.

“If we are going to give our citizens the opportunity to have a normal existence during COVID we need to make sure we change the way we think about it and that’s why I urge everyone to be patient … and not take those drastic measures because it just dashes confidence when people cant rely on borders staying open.”

The Premier said there was no reason to tighten any COVID-19 restrictions in NSW at this time but admitted the “situation is evolving”.

Two weeks ago Ms Berejiklian flagged a relaxation of restrictions around standing and drinking outdoors by March 17 barring any new outbreaks in the state.

NSW has reached its vaccination rollout targets with about 37,500 people being jabbed in the first three weeks.

About 35,000 of those people, mostly frontline workers involved in hotel quarantine, received the Pfizer vaccine, and the rest the AstraZeneca.

Ms Berejiklian said the rollout will ramp up.

“We are aiming to have 80,000 jabs take place in NSW in the next three weeks, of that 35,000 will be the second of the first jab,” she said.

The Pfizer vaccine is administered in two doses, at least three weeks apart.

-ABC