A COVID-19 cluster in Sydney's CBD has grown to 28 after two more members of a city gym tested positive.
NSW recorded seven new cases overnight on Sunday with five infections linked to the fitness hotspot including a close contact of a prior diagnosed member.
One new case is a returned traveller in hotel quarantine while a student at a western Sydney high school has also tested positive.
St Paul's Catholic College in Greystanes will be closed on Monday for cleaning, NSW Health said on Sunday.
People who attended the City Tattersalls gym in the Sydney CBD between 8am and 2pm on 19, 21, 23, 24 and 25 August are now considered close contacts and must isolate themselves and get tested immediately.
People who exercised at Virgin Active gyms on Pitt and Margaret Streets between 5pm and 6.40pm on 25 and 26 August are also urged to remain alert.

The Tattersals Fitness Centre in the CBD in Sydney. Source: AAP
Authorities are also investigating the source of an infection acquired by a staff member at the Surry Hills Police Cells Complex.
An alert issued by NSW Health said the Health and Forensic Mental Health Network is taking appropriate health and safety measures.
As a precaution, NSW Health has advised people living or working in the Greater Sydney metropolitan area and Central Coast to refrain from visiting aged care facilities until 12 September.
The preventative measure to keep the virus from infiltrating nursing homes and affecting the vulnerable elderly residents will mean many will be denied a visit on Father's Day.
Meanwhile, three Sydney schools that closed on Friday after staff members contracted the virus will re-open on Monday.
They include Homebush Public School, Double Bay Public School and Ryde Secondary College.
There are 66 active COVID-19 cases in the state, including six who are in intensive care, of whom three are on ventilators.

Homebush Public School in Homebush, Sydney Source: AAP
People in Australia must stay at least 1.5 metres away from others. Check your state’s restrictions on gathering limits.
If you are experiencing cold or flu symptoms, stay home and arrange a test by calling your doctor or contact the Coronavirus Health Information Hotline on 1800 020 080.