People from Greater Sydney breaching lockdown may be responsible for an outbreak at a gathering at Blacksmith Beach in Newcastle on Friday night. "We believe there may have been people there from Greater Sydney and that's how it was introduced," Dr Chant said. Lake Munmorah Public School on the Central Coast is closed today after students tested positive to COVID-19.(Nick Moir) Dr Chant said the known cases in Newcastle did not explain the high levels of coronavirus detected in sewage in the Hunter region. "Our cases does not fully explain the detections and so we don't want anyone to be complacent that we have got the full picture at this stage," she said.