13 Aug 2020

Covid-19: Imported goods as outbreak source an unlikely theory - Professor David Murdoch

11:46 am on 13 August 2020

One of the countries top infectious disease specialists says it's unlikely the Covid-19 outbreak in Auckland originated from imported goods.

Covid-19 coronavirus particles, illustration.

(File image). Photo: AFP

The Ministry of Health is testing surfaces at Americold cold storage offices where one of the latest Covid-19 positive cases worked amid speculation that an item may have been contaminated.

Director-General of Health Ashley Bloomfield said the virus could survive within refrigerated environments for quite some time.

University of Otago professor of infectious diseases David Murdoch told Morning Report that we needed to keep an open mind considering the source is unknown yet.

University of Otago professor of infectious diseases David Murdoch.

University of Otago professor of infectious diseases David Murdoch. Photo: University of Otago

"I think on balance it's probably less likely, but certainly worth exploring."

While complete data and knowledge on this virus is not available yet, Prof Murdoch said we do know that many other viruses are able to survive at lower temperatures - even below freezing point - and lower humidity.

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There have been reports of other viruses being able to preserve for prolonged periods of time such as weeks or months, he said.

"We know that in cold temperatures above freezing that's for a few days, at ambient temperature certainly it can survive for a few days."

However, the other aspect to consider is the risk of someone coming into contact with it and being infected, he said.

"I've seen some of the messaging from the business that's been under investigation, saying about the protection their staff have as well. You can imagine a number of things would need to align for it to be transmitted to humans."

In terms of testing the workplace, Prof Murdoch said it was a challenging one because they would need to find the exact spot where the virus was among many things.

"The actual decision about what you actually test is a big one, but that's actually a common problem. There's a whole science around environmental testing and this is always an issue."

It was also tough to quantify the risk of virus-contaminated items but the bigger risk was aerosol transmission, he said.

"As far as I'm aware, there haven't been any clear descriptions of transmission from inanimate objects ... but we know that with other viruses, particularly those that cause common colds, that they are important."

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