COVID-19 spread not influenced by hot or cold weather: Study

By Rahul Vaimal, Associate Editor
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COVID-19 & Weather
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It is believed that weather has an influence in the environment in which the coronavirus survives before it gets into the body of a host. But recent research led by the University of Texas in the US found that weather does not play a significant role in COVID-19 spread.

The study shows that despite the weather condition outside being hot or cold the transmission of the COVID-19 virus from one person to another depends almost entirely on human behavior.

“The effect of weather is low and other features such as mobility have more impact than the weather. In terms of relative importance, the weather is one of the last significant parameters,” said Dev Niyogi, a professor at UT Austin’s Jackson School of Geosciences and Cockrell School of Engineering who led the research.

The research was published in the International Journal of Environmental Research and Public Health and it was co-authored by Sajad Jamshidi, a research assistant at Purdue University, and Maryam Baniasad, a doctoral candidate at Ohio State University.

In the study, the weather was defined as “equivalent air temperature,” that combines temperature and humidity into a single value. The scientists then examined how this value tracked with coronavirus spread in different areas in a time frame from March to July 2020, with their scale ranging from various countries, states, regions and the world at large.

In the county and state areas, the researchers also studied the travel habits of the population to understand the link between coronavirus infection and human behavior.

The human behavior was analyzed in a general sense and did not try to connect it to how the weather may have influenced it. The researchers adjusted their analysis pattern in each area to make sure that population differences did not make the result biased or unbalanced.

The scientists found that the weather had no significant role in contributing to the transmission of the COVID-19 virus when compared to other factors. At the county level, the importance of weather was less than 3 percent and there is no indication that a specific type of weather boosted the spread over another.

Human influence

On the contrary, the study showed a clear influence of human behavior and individual habits that contribute towards the spread of the virus.

Taking trips and spending time outside the home were the top two contributors to COVID-19 spread, with a relative importance of about 34 percent and 26 percent respectively. The next two important factors were population and urban density, with a significance of about 23 percent and 13 percent respectively.

“We shouldn’t think of the problem as something driven by weather and climate. We should take personal precautions, be aware of the factors in urban exposure,” Jamshidi said.

Ms. Baniasad, a biochemist and pharmacist, said that assumptions about COVID-19 could react with changing weather are concluded by studies conducted in laboratory settings on related viruses. “When you study something in the lab, it’s a supervised environment. It’s hard to scale up to society. This was our first motivation to do a more broad study,” she said.

Mr. Niyogi stated that one of the important lessons of the pandemic is the need to analyze it on the human scale, which means on a scale at which humans live their daily lives and this study is an example from such a perspective.