Hunter New England Health public health physician Dr David Durrheim confirmed the people who had been in close contact with a nursing staff member had been identified and isolated after a "very detailed risk assessment".

"This is something that we are going to find will happen - particularly as the virus spreads," Dr Durrheim said.

"We have a process where infection control in the hospitals, and in aged care facilities, that can help us make sure we identify all the close contacts."

Confirmed cases of COVID-19 are doubling in the Hunter every three-and-a-half days, in line with the numbers seen across NSW and Australia, Dr Durrheim said.

"It seems to be fairly steady and that is concerning. That means we are getting exponential growth in cases, and we haven't really seen a lot of community spread so far.

"There has only been a handful of cases in the Hunter New England area that either haven't come off a cruise ship, haven't flown back from overseas, or haven't been a direct household contact of a known COVID-19 case."

Of the total number of confirmed cases in the region, 29 had come from cruise ships, with more likely to follow.

"But the good news is that all of the folk who have become positive have followed public health guidance and been in strict home isolation," he said. "They have done a great job restricting spread in the community."

A woman in her 70s who tested positive after a cruise on the Ruby Princess died in Sydney on Tuesday.

The woman, who was transported directly to hospital from the Ruby Princess in Sydney on March 19, was one of the initial three passengers who were confirmed to be COVID-19 positive following testing of retained specimens from on-board the cruise.

It comes as NSW Health announced an additional 149 cases diagnosed in the state since 8pm on March 22.

It brings the total number of confirmed cases in NSW to 818.

Dr Durrheim could confirm cases of COVID-19 were "widely scattered" across the Hunter New England region.

"It's not that any area has not had a case," he said. "And this is the nature of when you bring people back from overseas, or off cruise ships - they come from everywhere, and so it really is everyone - every community needs to be on the alert. The reason we don't provide case details is unfortunately because public behaviour sometimes can be quite virile, and unhelpful, and people get targeted for doing the right thing.

"These people are heroes to us. If they are prepared to stay at home for 14 days to prevent the spread, the last thing I want is for them to be harassed. As long as we can track down their close contacts and get them in isolation, we are going to protect their privacy. But if we can't - if there is a community event where we believe the transmission has occurred and we can't track down the close contacts - we will of course let people know. If there is community risk we will let people know."

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