When the coronavirus pandemic begins, many people hope that hot summer temperatures can reduce its spread. Although summer doesn’t bring generous relief, but the link between weather and COVID-19 continues to be a hot topic.
The relationship between weather and COVID-19 is complex. The weather affects the environment in which the coronavirus must exist before infecting a new host. But it also affects human behavior, moving viruses from one host to another.
Research led by the University of Texas at Austin is further clarifying the role weather plays in COVID-19 infection, with a new study showing that temperature and humidity don’t play a major role in coronavirus transmission. .
That means whether it’s hot or cold outside, the transmission of COVID-19 from person to person depends almost entirely on human behavior.
“Low weather effects and other traits like mobility have more impact,” said Dev Niyogi, professor at the Jackson School of Geosciences and UT Austin’s Cockrell School of Engineering, who led the study. weather. “In terms of relative importance, weather is one of the final parameters.”
Research published October 26, 2020, in International Journal of Environmental Studies and Public Health.
Co-authors are Sajad Jamshidi, a research assistant at Purdue University, and Maryam Baniasad, a doctoral candidate at Ohio State University.
The study has defined weather as “equivalent air temperature”, which combines temperature and humidity into a single value. The scientists analyzed how this value tracks with the coronavirus spreading in different regions from March to July 2020, with their sizes ranging from states and counties of the United States, to countries, regions and the world in general.
At a county and state scale, the researchers also investigated the relationship between coronavirus infection and human behavior, using cell phone data to study travel habits.
The study has looked at human behavior in a general sense and did not attempt to connect it to how the weather may have influenced it. On each scale, the researchers adjusted their analyzes so that the demographic differences did not skew the results.
On the scales, scientists found that the weather had almost no effect. When it is compared to other factors using a statistic that breaks down the relative contribution of each factor to a particular outcome, the relative importance of weather at scale. seeds smaller than 3%, with no indication that a particular weather prompted more spread than others.
In contrast, the data show a clear influence of human behavior – and the overwhelming effect of individual behavior. Traveling and spending time away from home are the two leading contributors to COVID-19 growth, with relative importance at 34% and 26%, respectively. The next two important factors are population and urban density, with relative importance being about 23% and 13% respectively.
“We should not think of the problem as something weather or climate driven,” says Jamshidi. “We should take individual precautions, be aware of the factors of exposure to the urban environment.”
Baniasad, a biochemist and pharmacist, says that the assumptions about how the coronavirus will respond to the weather is largely informed by studies done in the lab on the viruses involved. She said that this study illustrates the importance of studies analyzing how coronaviruses spread across human communities.
“When you study something in the lab, it’s a supervised environment. It’s hard to scale out society, ”she said. “This is our first impetus to do a broader study.”
Marshall Shepherd, a professor of atmospheric science at the University of Georgia who was not involved in the study, says that the study provides important insights into weather and coronaviruses on scales.
“This important work clarifies some of the allusions to the weather-COVID-19 link and emphasizes the need to address scientific challenges at appropriate scales,” Shepherd said.
Niyogi says that one of the key lessons of the coronavirus pandemic is the importance of analyzing phenomena at the “human scale” – the scale at which people live every day. This study, he says, is an example of this kind of perspective.
“COVID, it’s confirmed, can change anything”, Niyogi said. “We looked at the weather and climate outlook as a system that we downsized, reduced and then looked at how it could affect people. Now, we’re flipping the case and upgrading, starting at the scale of human exposure and then going out. This is a new model we’ll need to study viral exposure and human environmental modeling systems involving new sensors and AI-like techniques. “
Reference: “A Global Scale Analysis of the US on weather, urban density, mobility, staying at home and using a mask on COVID-19” by Sajad Jamshidi, Maryam Baniasad and Dev Niyogi, date October 26, 2020, International Journal of Environmental Studies and Public Health.
DOI: 10,3390 / ijerph17217847
The University of Texas at Austin, NASA and the National Science Foundation funded the research.