Mona Vale Golf Club and Narrabeen North Public School have reportedly had cases, but neither venue appears on the NSW Health venue alert list.

The Northern Beaches Review understands that Narrabeen North Public School principal Ryan Shepheard has issued an email to parents to advise of the COVID-19 case.

Dr Chant said she was aware of the COVID-19 case at Mona Vale Golf Club.

"I was with the team when there were discussions about that," she said. "I think everyone's been deemed close contacts and there's been work and engagement with the premises."

Dr Chant said there are a number of reasons why not all venues are listed.

"Sometimes there is a delay because on the website we want to just get the information about whether they're close contacts or others ... our aim is to be very timely in getting that information up, I'll just follow up on that," she said.

"The only condition where it wouldn't be released publicly is where there are very clear records of everyone who was involved.

"Some sites where we've got absolutely everyone don't go on there because the list is becoming so long that there's a balance between people actually seeing the ones that need to be focused on as opposed to ones that don't. That's a challenge for us with so many venues.

"This is clearly a concerning situation. We are also taking a very cautious approach with identifying venues and that's something we've learnt because we don't want miss and let any case escape our reach."