Tangara School for Girls in Cherrybrook has closed its secondary campus until August 24 and its junior campus until at least Wednesday after the first COVID-19 case linked to the Opus Dei-connected school, a student, was diagnosed last week.

Five of the 14 cases recorded in NSW in the 24 hours to 8pm on Sunday were connected to the school - four students and a household contact of a case.

Four cases were previously confirmed and two more were identified after the 8pm deadline.

Of the 11 cases identified to date, seven are students and at least one is a teacher.

The source of the Tangara outbreak remained unclear, NSW Health said on Monday, and all Tangara secondary students and staff were in self-isolation and being tested.

Nearby St Agatha's Catholic Church in Pennant Hills is also undergoing deep cleaning after a parishioner who visited last Wednesday and Thursday tested positive to the virus, as is PharmaSave Pharmacy in Cherrybrook after an infected employee worked on Thursday.

The PharmaSave worker wore a mask during their shift.

Elsewhere, a western Sydney primary school has also closed after a student tested positive to COVID-19, as has a western Sydney childcare centre after a staff member's diagnosis.

All Bonnyrigg Heights Public School students are learning from home on Monday as the school helps NSW Health trace the close contacts of the student and cleans.

Last week, a student at the nearby Bonnyrigg High School tested positive to the coronavirus and was closed before reopening the day after on Wednesday.

A staff member of Kids' Early Learning Quakers Hill was also confirmed COVID-positive on Monday after working a shift at the facility while infectious last Monday.

A second student at Our Lady of Mercy College in Parramatta was also diagnosed after 8pm on Sunday with COVID-19, and the school campus closed.

Late on Monday the Education Department announced Batemans Bay High School would be closed for cleaning on Tuesday after a student tested positive to the virus.

NSW Chief Health Officer Kerry Chant has urged people to avoid large gatherings and says older school students are more likely to transmit the virus.

The decision to resume face-to-face learning in NSW amid the COVID-19 pandemic was predicated on research showing children transmitted the disease at minimal rates.

"The older the students are, they behave more like adults," Dr Chant told reporters on Monday.

"We still know and believe younger students such as primary school students are not likely to be infecting (others) but as you get older ... an 18-year-old at school is more like an adult in terms of their characteristics, the risks of transmission."

Of the new NSW cases on Monday, one is in hotel quarantine and one has no known source, prompting Premier Gladys Berejiklian to again plead for caution.

"It's very difficult when people have attended a number of venues in one night for the contact tracers to do their work - we're in a state of high alert, we don't want to impose further restrictions," Ms Berejiklian said.

NSW Health over the weekend also advised staff who had contact with a Hornsby Hospital physician to self-isolate for 14 days after the staffer worked in the hospital's emergency department on Thursday from 11am to midnight while infectious.

Dr Chant said it's believed the physician did not catch the virus in the hospital.

Meanwhile, six people have been charged and 11 have been fined $1000 for breaching COVID-19 public health orders over the weekend.

Australian Associated Press