SA Health has linked the positive coronavirus case at Woodville High School to the Parafield cluster through the pizza bar that was at the centre of South Australia’s brief lockdown last week.

Authorities announced on Wednesday night that a girl who attends the high school had tested positive to COVID-19.

Anyone who was at the high school on Monday this week has been told to isolate immediately, as have all members of their households, until further notice.

About 1000 students have already gone into isolation.

On Thursday, SA deputy chief public health officer Mike Cusack said the case was part of the Parafield cluster, in which COVID-19 was spread by a cleaner and two security guards at the Peppers medi-hotel to close contacts and family members.

Dr Cusack said the link between the cluster and the student’s case was though to be though the Woodville Pizza Bar, where one security guard worked while infectious.

But Dr Cusack said the exact way the high school student caught the virus was yet to be established.

He said SA Health contact tracers had worked through the night in efforts to narrow down how the virus was transmitted and who might be at risk.

“We do believe that the case is linked to the Parafield cluster and does not represent unknown transmission in the community,” he told ABC Radio Adelaide.

“The link that we’re looking at, at this stage, is the pizza bar.

“But … the precise linkage in terms of dates, times, and so forth, we have yet to identify.

“We believe that the student was in school on Monday when they were likely to have been infectious.”

He urged anyone who has been in the Woodville area, and who developed COVID-19 symptoms, to self-isolate and get tested for the virus.

Anyone who attended Woodville High School on November 23 has been ordered into isolation with their household. Photo: Woodville High School

Education Department staff and industrial cleaning crews arrived at Woodville High School on Thursday morning to begin a deep clean.

South Australia was sent into lockdown last week partly on the basis of a lie the security guard had allegedly told contact tracers – that he had bought food there, but did not work there.

That claim led SA Health to believe the virus was extremely transmissible and that potentially thousands of people could have picked it up simply by getting food at the pizza shop.

The lockdown was cancelled when it became clear the man had worked there, and he has expressed remorse and apologised.

Chief public health officer Professor Nicola Spurrier is expected to provide more detail on the latest case later on Thursday.

–ABC