The Victorian Health Department has confirmed it advised Brooklyn abattoir Cedar Meats to close down, shortly after two cases of coronavirus were discovered at the factory in late April.
The state's Chief Health Officer Professor Brett Sutton said the Department of Health and Human Services acted quickly, after the second case linked to the abattoir was discovered.
"These cases were the very first indication of possible transmission, in a workplace," Prof Sutton said.
At that point, a thorough risk assessment was undertaken and work was rapidly scaled back, with only minimal staff on site to ensure the safe and appropriate management of the stock.
"I advised Cedar Meats should shut down, that all 350 staff should be considered close contacts, and therefore go into quarantine," Prof Sutton said.
"The source of infection is still under investigation, (but) we may not find out the original source."
Cedar Meats is now regarded as Victoria's most significant coronavirus cluster, with 62 cases linked to the abattoir.
The company processes and sells mutton, lamb, goat and veal to the European Union, North and South America, South-East Asia, China, the Middle East and Africa.
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Prof Sutton said an initial case of coronavirus, linked to Cedar Meats, had been reported on April 2, but the staff member did not identify the company.
"When he was identified on April 2, he was not working at Cedar Meats, and he had not been at Cedar Meats, while he was unwell," Prof Sutton said.
"It was not linked to the exposure site, because he hadn't spent any time there
"He could not have picked it up there, or transmitted coronavirus to anyone else."
Authorities were looking at a possible chain of infection but would not make presumptions about connections.
"We would not make a presumption of connection, or no connection," Prof Sutton said.
"We have no idea of his connection - it is part of a hypothesis that he may be connected through some unknown linkage outside work."
But he said authorities took what they had been told on face value.
"Everyone needs to tell the truth and say exactly where they have been, and when," Prof Sutton said.
"He said he wasn't at work; we take it on face value."
Prevention guidelines
Prof Sutton declined to comment on whether virus prevention guidelines at the abattoir had been adequate.
"I think it's for others to assess whether there were other elements around the work practices that contributed to the outbreak," Prof Sutton said.
The risk of transmission was intrinsically higher in meatworks, which were classified as an essential service.
"It's difficult to manage.
"The nature of the work means there are some workers who need to be in close contact, and for prolonged periods, so I think that's part of the risk of transmission here," he said.
"For certain purposes, (workers) will be closer than a metre and a half - the nature of the work brings them into a higher risk setting."
There was a limit on how far risks could be mitigated, in such settings.
Health Minister Jenny Mikakos said it was unlikely the virus was introduced by the first staff member, who tested positive.
"Unless the virus got into a car itself and went to Cedar Meats, there is no way it could be connected to that worksite," Ms Mikakos said.
"The whole time he was infectious, and he was unwell, he had not been at Cedar Meats.
"I am very satisfied everything has been handled properly."
Prof Sutton said that in America there had been hundreds of outbreaks in meatworks.
"They are intrinsically difficult to manage in terms of close contact, where people are on a working line who need to be in close contact," Prof Sutton said.
"The personal protective equipment they wear is difficult in hot and laborious conditions."
He said he understood Cedar Meats had screening systems in place and was spacing workers to the fullest extent it could.
'They had a generous policy to make sure staff weren't turning up to work unwell and had twice daily disinfection proceedures."
Federal inquiry
Meanwhile, Federal Agriculture Minister David Littleproud said the reasons for the outbreak were a question for the Victorian government.
"Obviously, I have some concern in which I'm investigating because Commonwealth departmental people were going through those abattoirs doing inspections," Mr Littlproud said.
"And I'm just getting to the bottom of when we were notified because obviously they make an inspection in one abattoir and move to another.
"I want to understand when we were notified and how we were notified because potentially, those Department of Agricultural personnel, who were in that abattoir and then moved to another one, potentially could have spread the virus."
Mr Littleproud said he wasn't pointing the finger, but wanted to get an understanding of how protocols could be put in place, to protect everyone.
"I can say standards are in place in all our abattoirs and people should not fear any meat that was processed through the abattoirs," he said
"It cannot be transmitted through processed meat, that's been quite clear."
Mr Littleproud said he was confident the Cedar Meats case was an outlier.
"I'm very proud of our meat processing sector," he said.
"I think they've been very forward-leaning making sure that they had social distancing protocols put in place within their facilities, not only on the floor of the abattoir but also in their lunchrooms and making sure that people are distanced out.
"They need to keep supplies moving through to make money, and they need to keep health standards up."
He said the sector had led the way, in preparing for the outbreak.
"I'm very confident that our meat processing sector will hold up, and our supply chains will continue to hold up to the demand, not only here but internationally."
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