Four new cases were recorded in the 24 hours to 8pm on Sunday including three returned travellers in hotel quarantine and one linked to a known cluster.

The locally acquired case is a close contact of a previous case who attended the Eastern Suburbs Legion Club.

NSW Health acting director Christine Selvey said testing rates had dropped recently and urged people with the mildest symptoms to make sure they get tested.

"Testing numbers have dropped over the past two weeks and this is a concern particularly in areas like southwestern, western and southeastern Sydney," she said in a video update on Monday.

More than 9300 people were tested in the latest reporting period, down from 14,426 the previous day.

Although weekend test numbers usually drop, Sunday's figure is well below recent weekend numbers, which have been in excess of 20,000.

Premier Gladys Berejiklian implored people to not become complacent, saying every day is a battle against the virus.

"Remember we let our guard down earlier in the year and the Victoria situation arose unexpectedly," she told reporters in Sydney on Monday.

She also urged other states to help ease the burden of accepting returned travellers into hotel quarantine.

"We're doing so much more than other states combined," she said.

"I would love to see the other states take on their fair share."

NSW Health has again urged anyone feeling unwell, even with the mildest of symptoms such as a runny nose or scratchy throat, to get tested so community cases are identified as quickly as possible.

That message was even more important with NSW public school holidays starting on September 26, when many people will be travelling around the state.

NSW Health is treating 81 COVID-19 cases, including six in intensive care, three of whom are being ventilated.

Australian Associated Press