Expert says studies on risk of virus transmission through surfaces don't reflect real world
TORONTO -- Is it necessary to wear gloves outside, or wipe down groceries or mail to keep yourself safe from potential COVID-19 exposure?
It’s a question that has been posed since the beginning of the pandemic.
Numerous studies have been carried out over the past few months to measure how long the virus can live on surfaces, looking at its lifespan on different materials and how infectious it remains for longer periods of time. Some studies have found the survival rate to be a matter of hours, while others have found that the virus, under some circumstances, can survive for days on surfaces.
Emanuel Goldman, Professor of Microbiology, Biochemistry and Molecular Genetics at the New Jersey Medical School, wrote in a comment published in the scientific journal The Lancet last week, that he believes the risk of virus transmission through infected surfaces has been “exaggerated.”
A “comment” does not present new data found through experiments or studies, but simply provides scientific commentary.
Goldman believes the results of all of these studies on the lifespan of the virus on surfaces have been used to direct courses of action for the general public that the data itself doesn’t call for.
“It’s not that the studies are wrong, it’s that they’re the wrong studies,” he told CTVNews.ca in a phone interview.
“So the belief that there was a risk from inanimate objects and surfaces stems from experiments that were done where virus was placed on surfaces, and then at intervals of times subsequent to doing that, the amount of virus that was left was measured. Well and good, but the problem with those experiments was that the amount of virus that they started with was much, much orders of magnitude larger than what you’re going to find in the real world.”
He said some of the studies measured the lifespan of the virus on surfaces by placing as much as “a hundred thousand to 10 million virus particles on a small surface area” -- which he believes is far higher than the amount of virus particles that would be present in the average sneeze.
He had not come across any scientific literature that specifically measured how many virus particles that caused COVID-19 were in a sneeze, but stated that similar research regarding the common flu found that there are around 10-100 viral particles within a droplet from an influenza patient.
Goldman emphasized that he doesn’t think these studies on the surface life of the virus are a problem themselves, but said the way their results have been interpreted and applied is.
“The supermarkets won't take returns of anything that you buy now because of this. You have to pack your own bags because they're worried about this. And it’s, in ways little and large, it's directed behaviour in a way that's not justified by the data,” he said.
“And even worse, it distracts and takes people away from what really protects you against this virus and that’s the masks. That's where the emphasis has to be. That's what's going to save us.”
He said that while it’s “not impossible” to contract COVID-19 in the grocery store by handling something that had recently been coughed on by an infected person, “there’s so many steps that would have to happen.
“First, someone infected would have to deposit the virus on the thing you bought, then you'd have to buy it right after. And after touching it, then you'd have to touch your mouth, your nose, [or] your eyes, and all that within a relatively short period of time.”
This means a person could handle a cereal box with virus particles on it and still remain safe if they were following the main public health recommendations -- wearing a mask in a grocery store and washing their hands at home before touching their face at all.
Dr. Isaac Bogoch, an infectious disease specialist, also told CTVNews.ca that transmission of the virus through surfaces was not “the main mode of transmission,” but said he doesn’t believe there’s an issue with being extra cautious by doing things such as wiping down groceries.
“If that's what gets people through the day, if that's what enables people to go get groceries, if that’s what enables people to open their mail, so be it, that's totally fine,” he said. “I think the pendulum is swinging away from that, but I would certainly not shame people for doing that at all.”
He said no one study alone is able to pinpoint an exact risk of transmission, and that one needs to look at the big picture to get an idea of the risks.
“At the end of the day, the data that's emerging now, when we sort of take a step back and look at who's getting infected, where are they getting infected and how are they getting infected -- this is generally people who are in close contact with one another, typically in indoor settings, when people are in close contact with one another for prolonged periods of time,” he said. “That’s who's getting the infection.”
New infection rates are also significantly lower in Canada than in countries such as the U.S., contributing to a lower risk of encountering surfaces that were coughed or sneezed on by an infected person within an hour or two of another person touching that surface.
Goldman acknowledged that disinfecting surfaces and tools and wearing gloves are things that are necessary in a hospital setting. But his worry for the general population is that the surface transmission discussion is a “distraction,” and that people might actually be less likely to follow any health guidelines if they feel overwhelmed by instructions to wipe down everything.
“You see now people not using masks, partly because it was such an overriding concern with including the surfaces. It just gets to be too much,” he said.
“Just use common sense and focus mostly on protecting your airways and your breathing.”