Expert on risk of virus transmission across surfaces does not reflect the real world, says expert


TORONTO – Is it necessary to wear gloves outside or to wipe the grocery or the mail to protect yourself from potential exposure to COVID-19? This is a question that has arisen since the start of the pandemic.

Many studies have been carried out in recent months to measure the lifespan of the virus on surfaces, looking at its lifespan on different materials and its degree of contagiousness for longer periods. Some studies have shown that the survival rate is a matter of hours, while others have found that the virus, under certain circumstances, can survive for days on surfaces.

Emanuel Goldman, professor of microbiology, biochemistry and molecular genetics at New Jersey Medical School, wrote in a comment published in the scientific journal The Lancet last week, that he thought the risk of virus transmission through infected surfaces was “exaggerated”.

A “comment” does not present new data from experiments or studies, but simply provides scientific comments.

Goldman believes that the results of all these studies on the lifespan of the virus on surfaces have been used to guide the general public towards actions that the data themselves do not call for.

“It’s not that the studies are wrong, it’s that these are the wrong studies,” he told in a telephone interview.

“So the belief that there was a risk of inanimate objects and surfaces stems from experiments that were done where the virus was placed on surfaces, and then at subsequent time intervals, the amount of virus remaining was measured. That’s fine, but the problem with these experiments was that the amount of virus they started with was much, much greater than what you will find in the real world. ”

He said that some of the studies measured the lifespan of the virus on surfaces by placing up to “one hundred thousand to ten million virus particles on a small surface” – which he said was much higher than the amount of virus particles that be present in the middle sneeze.

He had found no scientific literature that specifically measured how many COVID-19 viral particles were in a sneeze, but said similar research into the common flu had revealed that there were about 10 to 100 virus particles in a droplet of flu. patient.

Goldman pointed out that he doesn’t think these studies of the surface life of the virus are a problem in itself, but said the way their results have been interpreted and applied is.

“Supermarkets will not accept the return of everything you buy now because of this. You should make your own bags as they are worried about it. And that is, in a big and small way, it is behavior directed in a way that is not justified by the data, “he said.

“And worse, it distracts and keeps people away from what really protects you from this virus and the masks.” This is where the emphasis should be placed. This is what will save us. ”

He said that while it is “not impossible” to get COVID-19 at the grocery store by handling something that has been recently touched by an infected person, “there are so many stages that should happen.

“First, an infected person should drop the virus on the thing you bought, and then you should buy it right after. And after touching it, you should touch your mouth, your nose, [or] your eyes, and all this in a relatively short period of time. ”

This means that a person could handle a cereal box containing viral particles and remain safe if they followed the main public health recommendations – wear a mask in a grocery store and wash their hands at home before touching their face. .

Infectious Disease Specialist Dr. Isaac Bogoch also told that transmission of the virus across surfaces is not “the primary mode of transmission,” but said he did not believe it be extremely careful when doing things such as wiping groceries.

“If this is what allows people to spend the day, if it is what allows them to go shopping, if it is what allows them to open their mail, then so much the better is absolutely correct, “he said. “I think the pendulum is moving away from that, but I certainly wouldn’t be ashamed of people doing it. ”

He said that no single study can determine an exact risk of transmission and that you have to look at the big picture to get an idea of ​​the risks.

“In the end, the data that emerges now, when we take a step back and look at who is infected, where are they infected and how are they infected – these are usually people who are in close contact with each other others, usually indoors, when people are in close contact with each other for extended periods of time, “he said. “It’s who gets the infection.” ”

New infection rates are also much lower in Canada than in countries like the United States, which helps reduce the risk of encountering surfaces that have been coughed or sneezed by an infected person within an hour or two. ‘another person touching this surface.

Goldman recognized that disinfecting surfaces and tools and wearing gloves are necessary in hospitals. But his concern for the general population is that the discussion of surface transmission is a “distraction” and that people might actually be less likely to follow health guidelines if they feel overwhelmed by the instructions to clear everything .

“You can now see that people don’t use masks, in part because it was a primary concern to include surfaces. It just gets too much, ”he said.

“Just use common sense and focus primarily on protecting your airways and your breathing. “


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