Staff and students at a Central Coast primary school, a high school in southern Lake Macquarie and a school near Newcastle have been told to get tested and isolate, as contact tracers scramble to assess transmission risks.
The new cases have prompted Premier Gladys Berejiklian to announce a one-week snap lockdown for the Hunter and Upper Hunter region.
It comes after five people died of Covid-19 and local case numbers jumped by 262 - the state's worst day of the pandemic this year.
Health authorities believe the Hunter infections can be linked to a gathering ay Blacksmiths Beach on Friday night.
The principals at Lake Munmorah Public School and Morisset High School wrote to parents overnight, advising them that two students tested positive to COVID-19 at the primary school, and one at the high school. Two of the students are siblings.
“The safety and wellbeing of our staff and students is of paramount importance to us at all times. As such we will continue to work closely with NSW Health to ensure that all necessary health advice is adhered to," Lake Munmorah Public School Principal Narelle Baldwin posted to Facebook.
“While we recognise this will be disruptive and inconvenient for families, it is important that we follow NSW Health advice and take all necessary precautions to minimise the risk of further transmission to support our community.”
Maitland Christian School near Newcastle is the latest school to temporarily close, with parents advised this morning to "collect your children immediately, even if you are an essential worker."
Hunter region hit with Covid alert after vaccines sent to Sydney
The new cases and snap lockdown comes a day after the Hunter region was put on high alert because fragments of the virus were detected in the sewerage.
It follows the controversial decision to divert Pfizer doses away from regional areas to vaccinate year 12 students in Sydney.
The move was met with intense backlash as thousands of vaccine appointments were cancelled at vaccine hubs across the state, including the centre at Belmont, which services the Hunter.
Until now, there have been no recent local cases in the Hunter and it wasn't part of the lockdown for Sydney and surrounding areas.
The Belmont, Burwood and Shortland plants cover more than 400,000 people across Newcastle, Lake Macquarie and southern Port Stephens.
The Central Coast is included in the Greater Sydney lockdown and has been subject to strict restrictions.
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