NSW health authorities are rushing to contact about 7000 people possibly exposed to a COVID-19 case as Victoria enters a snap five-day lockdown.

Anyone who visited Melbourne Airport, Terminal four from 4.45am to 2pm on Tuesday of this week is being urged to immediately isolate for 14 days and seek COVID-19 testing.

NSW Health urged all household contacts of those people to immediately isolate until a negative result is returned.

A full list of the venues of concern is available at the Victorian Department of Health and Human Services website.

“NSW Health is currently contacting approximately 7000 people who have entered NSW from Victoria after attending these venues of concern, to ensure they are aware of the requirements,” a spokesperson said on Friday.

“If you have been to any of these locations at the times listed you are at risk of COVID‑19 so please follow the health advice provided.”

Sydney Airport is bracing for a rush, as Victoria’s latest COVID-19 outbreak reached 13 cases, plunging the state into a snap lockdown from 11.59pm Friday until Wednesday.

The cases are linked to a Holiday Inn at Melbourne Airport that was being used as a quarantine hotel for returned travellers.

All of Melbourne Airport’s Terminal Four has been declared a virus alert spot.

NSW Health said the mandatory passenger declaration from all air and rail travellers since February 4 was helping contact tracers reach the affected travellers.

On Friday morning, NSW Premier Gladys Berejiklian described Melbourne’s outbreak as a “concerning, evolving situation” but said tightened security measures at Sydney Airport were adequate “at this stage”.

“That’s how we intend to proceed at this stage, there’s no reason for us to close the border,” she said on Nine’s Today show.

Ms Berejiklian said it took daily case numbers in excess of 150 to close the NSW-Victorian border in 2020, compared to the Melbourne Airport cluster’s total of 13 cases.

“We’re nowhere near where we were when NSW took the decision last time,” she said.

“Lockdown, as far as NSW is concerned, or a border closure, is a last option, not a first option, and we’re doing everything we can to keep the virus out of NSW.”

However, several states have closed their borders to greater Melbourne in the immediate aftermath of the snap lockdown.

Queensland has declared greater Melbourne a COVID hotspot for the next 14 days, meaning people from the 36 local government areas in and around Melbourne are not allowed to enter from 1am Saturday.

Heath authorities in Queensland are tracing 1500 people who have come to the state after travelling through Melbourne Airport’s Terminal Four.

The Northern Territory government also declared greater Melbourne a coronavirus hotspot on Friday.

Any travellers from the city arriving in the Territory from 10.45am were being directed into 14 days of mandatory quarantine.

Western Australia has reinstated a hard border with Victorians, while South Australia’s border remains closed to greater Melburnians.

It comes as several COVID-19 restrictions ease from Friday in greater Sydney, which includes the Blue Mountains, Wollongong and Central Coast.

Face masks are no longer mandatory in hair and beauty salons, places of worship and gaming rooms.

People working in hospitality venues like cafes, bars, pubs and restaurants will also no longer need to don a mask.

However, masks remain mandatory on public transport, in taxis and in ride-sharing services.

Also among Friday’s eased restrictions is the replacement of the four-square-metre rule with the two-square-metre rule, though that excludes gyms.

On Friday, NSW recorded its 26th day in a row with no locally acquired cases.

A total of 14,518 tests were performed in the 24 hours to 8pm Thursday.

-ABC