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Working with researchers from the University of California, Davis, the U. scientists tested how temperature and humidity affect the structure of such particles on surfaces and found even moderate temperature increases broke down the structure of the virus.
The findings were published in a Nov. 28 paper in the journal Biochemical Biophysical Research Communications.
Michael Vershinin, assistant professor in the Department of Physics & Astronomy at the University of Utah, co-authored the paper along with U. colleagues Abhianyu Sharma, Benjamin Preece, Heather Swann, and Saveez Saffarian. Vershinin told KSL.com the study has earned national and international attention since it was published.
"We've been very happy with the impact this is making," he said.
According to a U. news release about the findings, the SARS-CoV-2 virus needs to maintain its structure, "a specific web of proteins arranged in a particular order," to remain infectious. When that structure falls apart, it's harder to transmit the virus.
"You would expect that temperature makes a huge difference, and that's what we saw. To the point where the packaging of the virus was completely destroyed by even moderate temperature increases," Vershinin said in the release. "What's surprising is how little heat was needed to break them down — surfaces that are warm to the touch, but not hot. The packaging of this virus is very sensitive to temperature."
The Utah researchers not only studied the impact of temperature on the virus, but created the virus-like particles used in the study. This allowed them to study SARS-CoV-2 without the risk of accidental outbreak. The process of that creation was detailed in a separate paper published this month.
You would expect that temperature makes a huge difference, and that's what we saw.
–Professor Michael Vershinin, University of Utah
"If you think about what a virus is, it typically has a genome and then it has some packaging," Vershinin explained. "The survival of the virus as it travels from host to host is, in a lot of ways, related to how the genome is packaged. So it is not a 100% replica, but it is a very good model for how the virus handles the environment." The particles were essentially the virus without its genome.
The scientists found that humidity had little effect on surfaces, but they still believe humidity has an impact on transmissibility when the virus is in the air.
"From the very beginning, people have theorized that the major effect of humidity on viruses, and the reason why it would matter, is because it affects how these aerosols dry out," Vershinin said.
SARS-CoV-2 rides along on aerosol droplets that are ejected when people speak, breathe, cough and sneeze; scientists believe those aerosols linger longer in humid conditions and evaporate faster in dry conditions.
So does this study mean it is easier to transmit the coronavirus in cold weather?
"It is the implication of this work that is likely the case," Vershinin said, though he cautioned there are several steps between his research and proving that definitively. But the U. study "does not exist in a vacuum," he said, and other research also suggests that.
Vershinin said the U. study is important because it examines the virus at a much more granular and specific level than most others. "Connecting it to the mechanism, exactly how this happens — showing that at least one of the mechanisms likely involves degradation of the virus particles themselves, at the individual level, is very important because it helps us understand what's actually going on."
He said scientists have made great progress in understanding the virus for such a short period of time, but believes that SARS-CoV-2 and other coronaviruses will continue to be actively studied for years to come. "Viruses are complicated," he sad. "The vaccine is not the end of inquiry, and not the end of questions."