TWO inmates at Loddon prison are in quarantine, according to the Community and Public Sector Union.
CPSU spokesperson Julian Kennelly said both prisoners were asymptomatic and were awaiting the results of COVID-19 tests.
They were at Ravenhall Correctional Centre before Loddon prison.
Mr Kennelly said the union was very confident in the protocols, which he said were not dissimilar to what was happening in the broader community.
"We're doing the best we can," he said.
THE prison officer who tested positive to COVID-19 had been self-isolating since Thursday, a Department of Justice and Community Safety spokesperson said.
The worker - who was employed by Ravenhall Correctional Centre managers GEO - had been notified they were a close contact of a positive case.
The department spokesperson said measures were being taken to limit the potential spread of the virus and keep staff and prisoners safe.
"Precautionary measures include thorough cleaning, contact tracing and lockdown procedures," the spokesperson said.
It is not known how long the six prisons will be locked down, beyond this evening.
The Bendigo Advertiser understands all new prisoners will have to be tested and spend 14 days in protective quarantine.
It is understood all staff and professional visitors will be subjected to screening and temperature checks before entering a facility. Those who present with COVID-19 symptoms or risk factors will be turned away.
The Bendigo Advertiser understands there is some possibility the affected worker at Ravenhall came into contact with prisoners who were moved to other facilities.
Prisoners believed to have come into contact with the worker would be placed into quarantine.
LODDON is one of six Victorian prisons in lockdown after a prison officer at Ravenhall Correctional Centre tested positive for COVID-19.
Hopkins Correctional Centre, Langi Kal Kal, Barwon Prison, Fulham and Loddon are understood to have been placed into lockdown as a precaution.
The Ravenhall officer's contact with other staff and prisoners is under investigation.
A Corrections Victoria statement said the Department of Health and Human Services had been notified and contract tracing was underway.
Impacted staff and prisoners were being notified, according to the statement.
Corrections Victoria said a number of measures had already taken place, in line with its COVID-19 management plans.
They included placement of potential prisoner contact in quarantine units, contact tracing and thorough cleaning.
Malmsbury Youth Justice Centre went into COVID-19 lockdown on Sunday after a worker tested positive to COVID-19.
All the young people at the centre who were tested for the virus have tested negative.
The prison officer at Ravenhall does not work in the youth justice system.
The Bendigo Advertiser understands the Malmsbury Youth Justice Centre worker was an education coordinator, whose role involved working one-on-one with children and justice workers.
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