New German research into a coronavirus outbreak at the country's biggest abattoir has shown COVID-19 can be transmitted over a radius of more than eight metres.
The research comes as peak industry and union bodies have condemned the sector being singled out as a coronavirus hotspot.
The Helmholtz Centre for Infection Research (HZI), the University Medical Center Hamburg-Eppendorf (UKE), and the Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology (HPI), studied the origins of the first COVID-19 outbreak, in May, at Tonnies abattoir complex.
"Our results indicate that the conditions within the deboning work area of the meat processing plant - namely the low temperature, low fresh air supply and constant air circulation through the air-conditioning system in the hall, together with hard physical work - promoted the aerosol transmission of COVID-19 particles over greater distances," HPI group leader Professor Adam Grundhoff said.
"It is very likely that these factors in general play a significant role in the globally occurring outbreaks in meat or fish processing plants.
"Under these conditions, a distance of 1.5 to 3 metres alone is obviously not sufficient to prevent transmission."
The results reconstructed the initial transmission events in May 2020.
Originating from a single employee, the virus was transmitted to several other workers within a radius of more than eight meters.
The main transmission took place in the deboning area for beef quarters, where air is circulated and cooled to ten degrees.
In contrast, the housing conditions of the workers did not play a significant role during the investigated phase of the outbreak.
Meanwhile, the Australasian Meat Industry Employees Union and Australian Meat Industry Council have both condemned what they said was an over emphasis on coronavirus outbreaks in the abattoir and meat processing sector.
Coronavirus cases have been linked to Cedar Meats and JBS' Brooklyn abbatoirs, Somerville Retail Services, Tottenham, Bertocchi Smallgoods, Thomastown, the Ausralian Lamb Company, Colac, Diamond Valley Pork, Laverton North and Don KR, Castlemaine.
AMIEU state secretary Paul Conway said some processors, such as JBS and Cedar, had since reopened.
"From my perspective, the meat industry is an essential part of manufacturing in Australia and the last vestige of that sector," Mr Conway said.
The car and clothing industries had gone, but if they were still operating they would most likely to have been affected by coronavirus, in the same way the meat processing sector had been.
"You would have seen similar clusters, but there seems to be an over-concentration of interest in the industry with the most outbreaks," Mr Conway said.
"On the whole, especially from the union side, the industry has done their utmost to keep coronavirus, out of works," he said.
"If you take JBS as a case in point, they are using thermal imaging, face masks, hand sanitiser, social isolation in the lunchrooms adnd they've been corresponding to us.
"Yet has still got in there."
Mr Conway said when Cedar Meats announced its first case, comments were made about it being the tip of the iceberg.
"I said they are the first, but they won't be the last."
He said many of those who contracted coronavirus, and then went to work, were asymptomatic.
"People contract it out in the community, and then they work, if not on top of each other, in fairly close proximity," Mr Conway said.
He said there could be cross-pollination of the virus through vets and meat inspectors.
And the Australian Meat Industry Council has rejected claims the meat industry was a responsible party in the transmission of coronavirus, after recent outbreaks in Victorian processing plants.
Chief executive Patrick Hutchinson said from as early as January AMIC started implementing robust risk management guidelines, to incorporate COVID-19 safety plans for the industry's total supply chain and retail network.
The meat industry was uniquely positioned as one of the premier industries where food safety and hygiene was part of its core business.
"This is a public health issue and a community transmitted virus, not a meat industry or food safety issue," Mr Hutchinson said.
There had been an over-emphasis of cases being linked to the Australian meat industry.
The virus was being transmitted in the community, not generated from within any particular industry.
"The Australian meat industry has extremely controlled measures in place and should not be viewed through the same lens as meat industries in other countries," Mr Hutchinson said.
"The actual percentage of staff that make up the total amount of cases, within a "cluster" linked to a meat processing facility, is small relative to total community transmissions.
In some cases it was less than three per cent, across AMIC's red meat and smallgoods members.
"We do not want to see the shut-down of our industry due to changing rules that we have limited to no control over," he said.
"As such, we are working closely with the Department of Health and Human Services (DHHS) and those members that have been impacted to ensure minimal interruption to business operations and communicate a clear set of expectations and response procedures."
Victoria University public health expert Professor Max de Courten said the operators of abattoirs and meat processing plants must continue to employ strict hygiene and social distancing rules.
He said it meatworks fitted the criteria of a high-risk working environment, allowing coronavirus to spread rapidly.
"They are breeding grounds for super spreaders," Prof de Courten said.
Plants were humid, often had poor ventilation, and employees worked close together, for long periods.
While it was easy to say workers should wear masks and practice social distancing, in theory that wasn't always possible.
"If the government shuts down the whole place, companies need to find ways of maintaining some level of operations, consistent with those protective measures," he said.
"There is nothing more magic than good infectious disease control measures, the principal is to reduce the potential spread of the virus."
He said workers could unwittingly pass on coronavirus, when they did not realise they were infected.
"You can have the virus, and for a couple of days you feel fine and you go back to work, but you are spreading it."
He said people should not be quick to blame those who had spread the virus unwittingly.
"There is no way, in the beginning, that you would know you have picked it up."
Deep cleaning of facilities was very effective and could see them reopened in two to three days after it was completed.
"It's the staff that need to be quarantined."
Have you signed up to Stock & Land's daily newsletter? Register below to make sure you are up to date with everything that's important to Victorian agriculture.