Can the coronavirus survive on frozen food?
It’s the question New Zealand is scrambling to answer after its mystery coronavirus outbreak was linked to a cold storage facility in Auckland.
It comes on the heels of Chinese state media claiming the coronavirus was detected on some frozen chicken wings imported from Brazil.
New Zealand’s director-general of health Dr Ashley Bloomfield confirmed on Wednesday that a cold storage facility where one of the confirmed virus cases worked will be subjected to “environmental testing”.
“We do know from studies overseas, that actually, the virus can survive in some refrigerated environments for quite some time,” Dr Bloomfield said.
“In general, the role of surfaces for transmitting the virus has probably been overemphasised in the past. There’s much more focus now on transmission in indoor environments, and respiratory droplets.”
Can COVID-19 be passed on via frozen food?
It might be possible, but it’s very, very unlikely.
Chris Burrell, a virologist and former emeritus professor at the University of Adelaide, said scientists often took advantage of viruses’ ability to survive for longer in freezing temperatures.
“In the lab, if we want to keep a virus sample infective then we freeze it,” he told The New Daily.
In the right conditions, some viruses can survive for decades – even in dead bodies, he said.
In 2005, American scientists shocked the world by recreating the 1918 influenza virus that killed at least 20 million people worldwide by using pieces of genetic material from frozen corpses.
But before you panic and throw out your frozen fish fingers, this does not mean COVID-19 can survive on any cold surface.
When scientists store viruses in freezers, the samples are normally kept in liquid nitrogen temperatures (about minus 150 degrees Celsius), said Associate Professor Ian Mackay from the University of Queensland.
“When we do that, those viruses can last for years. But those viruses are at high concentration, purified and in the ideal material for them to survive,” he said.
“They’re not freeze-thawed and left in the sun, or left in plastic or touched by lots of hands.”
The chance of contracting COVID-19 by handling frozen food is therefore incredibly slim.
So far, there has been no evidence you can catch it through food or food packaging.
“I’m sure it’s worth investigating, but it is a less likely cause of the infection,” Professor Burrell said.
“A person would be much more likely to get it if someone sneezed in their face.”
So how did NZ’s mystery cases emerge?
No one knows yet.
Professor Mackay suggested New Zealand’s surprise COVID-19 cases may have come from “leaky quarantine” housing returned travellers or people who were unknowingly passing the virus around without showing any symptoms.
“Even asymptomatic people can have infectious virus in them, and they can breathe it out and leave it on surfaces,” he said.
Another possible but less likely scenario, he said, was the presence of ongoing transmission around the country.
NSW infections ‘could be ten times higher’
The possible spread of the coronavirus on foods comes amid warnings of the “silent transmission” of the disease in the community.
An leading epidemiologist told the ABC the true number of infections in NSW could be up to ten times higher than the daily reported tally.
As fears of community transmission grow, University of Melbourne epidemiologist Tony Blakely said many more NSW people could be infected but had not presented for testing.
“So, if they’ve got an average of 20 [cases per day] in the last week, that means that at any one point in time, there’s about 200 other cases out there that we don’t know about. Basically, 10 times the daily count,” Professor Blakely said.
On Thursday, NSW reported 12 new cases of COVID-19, including three that were acquired locally without a known source.
Professor Blakely said many of the unreported cases would also be mystery infections from unknown sources.
Victoria’s ‘patient zero’ was Rydges staffer
A night staffer at Melbourne’s Rydges on Swanston has been revealed as ‘patient zero’ in a media report.
Leaked emails obtained by the Melbourne Age show a night duty manager – not a security guard – was believed to be the link between the hotel quarantine and the community spread.
After becoming infected, the night manager passed the virus onto security staff who spread the disease to families in the northern and western suburbs of Melbourne, the report claims.
It’s not known how the hotel staffer was infected but it’s believed a returned traveller in hotel quarantine may have been the source.
The emails show a considerable effort was made to contain the spread after the manager came down with the illness on May 25.
Seven security guards contracted to patrol the hotel were stood down immediately and told to get tested and go home to isolate and a small number of hotel staff and health workers were told to do the same, The Age reports.
Five of those security guards tested positive but by then had already brought the virus to the community.
The Age says the email chain shows officials initially mistakenly reported that a security guard was the first positive test.
There is no suggestion the night manager became infection due to improper behaviour.