NSW Health on Friday said two of the students attended Cerdon College in Merrylands, one attended Mary Immaculate Catholic Primary School in Bossley Park and another is from Freeman Catholic College at Bonnyrigg Heights.

All cases are associated with the Thai Rock cluster, with two also linked to Our Lady of Lebanon church.

The schools are currently closed while contact tracing and cleaning is underway with close contacts also directed to self-isolate for 14 days.

It comes as new COVID-19 measures have come into effect for hospitality venues in a bid to curb the spread of the virus.

The changes include mandatory sign-ins, prepared COVID-safe plans, a cap of 300 people and maximum group bookings of 10.

Caps on private indoor and outdoor gatherings remain at 20, but weddings and corporate events are now capped at 150, and funerals and religious gatherings at 100.

Customer Service Minister Victor Dominello said about 31,000 businesses had so far registered their COVID-safe plans with the government.

Liquor and Gaming NSW has conducted 1311 COVID-safe inspections to date, resulting in three fines. More inspectors would be on the beat around NSW from Friday.

Mr Dominello also encouraged members of the public to dob in non-complying venues.

"It's not Dry July for me anymore, it's Compliance July," he told reporters on Friday.

"This virus does not stand still and nor should the government, we need to be able to adapt."

Seven new cases of COVID-19 were reported in NSW in the 24 hours to 8pm on Thursday from a record 36,169 tests, with three people currently in intensive care.

Of the seven, six are associated with the Thai Rock restaurant in southwest Sydney's Wetherill Park - taking the size of that cluster to 52.

The other case remains under investigation.

NSW Health's Dr Jeremy McAnulty said a previously-confirmed COVID-19 case had visited Costco supermarket at Marsden Park on July 19. Any Costco shoppers on that date have been encouraged to seek testing if symptoms develop.

The Crossroads Hotel cluster in Casula remains at 56 people.

"Key messages for the community are to avoid non-essential travel and gatherings. Of particular concern is transmission in venues such as hotels and restaurants, the gym and social gatherings," Dr McAnulty said in a statement on Friday.

The four students who tested positive to COVID-19 were not included in Friday's numbers.

An aged care facility in Sydney's inner west, Ashfield Baptist Homes, has also been closed to visitors after a staff member connected to Thai Rock tested positive.

Meanwhile, the NSW Nurses and Midwives' Association on Friday welcomed the requirement for hospital staff to wear masks if they are within 1.5 metres of patients.

The decision was made after NSW Health moved the risk level to amber because of the increase in community transmission of COVID-19.

Northern Territory Chief Minister Michael Gunner, meanwhile, on Thursday declared Port Stephens a coronavirus hotspot, meaning anyone who has been there in the past 14 days must undergo two weeks of supervised quarantine upon arrival in the NT.

Tomaree Public School and High School, Goodstart childcare centre at Anna Bay, Woolworths supermarket at Salamander Bay Village, and Fingal Bay Cafe and Takeaway have all undergone deep cleaning after being exposed to a person with coronavirus.

People who travel into Queensland from Fairfield in Sydney's southwest, along with those from Liverpool, Campbelltown and the state of Victoria, will also be directed to hotel quarantine.

Australian Associated Press