Five of the cases recorded in the 24 hours to 8pm on Thursday are returned overseas travellers in hotel quarantine.

The locally acquired case is a household contact of a case who attended Liverpool Hospital and was in isolation while infectious.

There are now 21 cases linked to the Liverpool Hospital dialysis cluster.

NSW Health on Friday said tests are ongoing on a potential false-positive case from the Murrumbidgee area. The person and their close contacts remain in isolation while further tests are undertaken.

The health department has again urged anyone feeling unwell - even with the mildest symptoms - to come forward and get tested after a drop in testing numbers in the latest reporting period.

There were 16,843 tests recorded on Thursday compared to 20,411 the previous day.

Meanwhile, Queensland Deputy Premier Steven Miles has denied any communication breakdown with NSW.

It follows NSW Premier Gladys Berejiklian's comments on Thursday that all conversations with Queensland Premier Annastacia Palaszczuk over borders had ceased again.

Mr Miles said Queensland's chief health officer speaks with her NSW counterpart pretty much every day and he speaks with his counterpart most days as well.

"There is good and strong ongoing collaboration between the two states as there needs to be; we share a highly populated border," Dr Miles said.

But he refused to comment on the relationship between the premiers.

The two premiers have been at loggerheads for months over the border issue, with Ms Berejiklian saying there is no logical reason for the COVID-19 restrictions to remain.

"The door is completely shut as far as Queensland is concerned," Ms Berejiklian said.

"(It's) locked, bolted and no conversations are continuing unfortunately."

Australian Associated Press