Police find no Covid-19 breaches at Sydney's Tangara school as NSW reports nine new cases

The New South Wales police have found there were no breaches of Covid-19 restrictions at Sydney’s Tangara School for Girls, as the number of cases linked to the cluster grew to 21.

On Friday, NSW Health announced a further nine new cases in the state, including one more student from Tangara, another staff member at Liverpool hospital, a person who worked at Dooleys Lidcombe Catholic Club, and two household contacts of known cases. One other infection was from an unknown source, and four were overseas-acquired.

The source of the initial infection at the Tangara school is still unknown, though reports have linked the outbreak to a study and prayer retreat attended by several students who later tested positive for the virus.

On Wednesday, the Catholic Opus Dei study centre linked to the Tangara cluster was closed for cleaning after it confirmed that five Tangara students – some of whom later tested positive – had attended a religious study camp organised by the centre.

Another Catholic school, St Vincent’s College at Potts Point, was closed on Friday after a student was diagnosed overnight, and Our Lady of Mercy College in Parramatta was closed earlier in the week.

On Friday, NSW police said an investigation into whether Tangara school could have broken Covid-19 restrictions had found no breaches by the school. The investigation came after a parent anonymously called Sydney radio station 2GB and alleged the school had continued to hold choirs, mass and assemblies in contravention of restrictions over gatherings.

Related: NSW Covid-19 hotspots: list of regional and Sydney outbreak locations

In a letter to the school’s community posted on its website, Tangara’s principal, Rita Sakr, said there had been “misinformation” circulating during the “challenging and emotional period”.

“We have always followed the advice of NSW Health around Covid-19 and will continue to do so,” Sakr said.

She said the study centre was “a third-party provider of after school care, a homework centre and other activities and retreats for the community” and that the school played “no role in organising or monitoring attendees”.

Friday’s new cases took the total of infected healthcare workers at Liverpool hospital to three – after two were diagnosed on Tuesday. There are also two healthcare workers at Hornsby hospital who have contracted the virus.

NSW Health said in a statement that the risk to the general public and to other hospital staff was low. “There is no evidence of any ongoing risk to patients and staff from recent cases at Liverpool hospital and patients should continue to visit to receive the medical care they need,” they said.

But people who were at Liverpool hospital on 6 August from 7am to 3pm, 7 August from 7am to 3pm, or 8-9 August between 5am and 1.30pm are advised to monitor for symptoms and get tested should even the mildest symptoms develop.

Also on Friday, an independent special commission of inquiry into the handling of the Ruby Princess fiasco found several “serious errors” were made by a NSW Health expert panel in conducting a risk assessment of the cruise ship before it docked in Sydney Harbour on 19 March.

The final report, handed down on Friday by commissioner Bret Walker SC, found the expert panel made an “inexplicable” and “unjustifiable” decision to deem the ship low risk. The report also cleared the Australian Border Force and the home affairs department of any responsibility for the debacle.