Will warmer weather slow down the spread of the coronavirus?

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The weather here in Virginia and many parts of the US is beginning to warm as we work our way closer toward summer. Many are looking for some good news when it comes to stopping the spread of COVID-19 (SARS-CoV-2). Could warming weather help stop the spread of the new coronavirus similar to other viruses?

Turns out that is somewhat of a complicated question.

Preliminary research from one study has found that the new coronavirus didn’t spread as efficiently in warmer and more humid regions of the world as compared to colder areas. It should be noted that this data has yet to be peer reviewed, but provides some reason for hope.

The two researchers from the Massachusetts Institute of Technology, Qasim Bukhari and Yusuf Jameel, found that 90% of the infections caused by COVID-19 so far occurred in areas that are between 37.4 degrees and 62.6 degrees Fahrenheit with an absolute humidity of 4 to 9 grams per cubic meter (g/m3). The absolute humidity is a strict measurement of how much moisture is in the air, independent of temperature.

In addition, the study found that in areas with average temperatures greater than 64.4 Fahrenheit and an absolute humidity greater than 9 g/m3, the number of COVID-19 cases is less than 6% globally.

So what does this mean? Well, though research has shown that the virus may spread less easily in warm and humid conditions, it may not be the saving grace that many are hoping for.

Dr. James Weger-Lucarelli, a research professor from the Department of Biomedical Sciences and Pathobiology at Virginia Tech, believes that weather can affect the spread of SARS-CoV-2, but is unsure by how much.

"At higher temperatures, the virus is less likely to survive on surfaces," said Weger. "Seasonality is important for the transmission of many viruses, however it's unclear if this is true for SARS-CoV-2."

When looking at the climate of North America and Europe, two of the big hotspots right now of COVID-19, the effect of humidity on the spread may be minimal until June. This is when levels rise beyond what is needed to reduce the spread, according to the researchers of the paper.

Another issue researchers are finding is that numbers have been rising recently in areas warmer than 64.4 degrees on average. This reveals that in order to slow the spread, temperatures likely need to be much warmer.

"The temperatures might not get high enough in the NRV to have a really strong effect." said Dr. Weger-Lucarelli.

The average temperature typically exceeds 70 degrees from July to September in Blacksburg. Other areas from the Blue Ridge to the Piedmont can reach these levels from June to September. An additional month of help from Mother Nature.

Typically flu viruses diminish in high humidity and high temperatures. A viral particle, suspended in a droplet that is put into the air through a cough or even breathing, may be heavier during the warmer months and be pulled towards the ground. During colder, drier periods of the year the droplet that surrounds the particle may evaporate more quickly and allow the virus to remain in the air longer.

The window for temperatures needed to slow the spread, may be too small in northern portions of the US and Europe and even as far south as Virginia. Unfortunately, if the virus is still spreading elsewhere, the issue would only continue into the colder months late in the year only helping to bring about another wave of contagion.

Overall, the environmental influence on the spread of the virus will likely not be enough. Social distancing and proper quarantine measures are ultimately the most important limiting factors. Until a vaccine is created, it will take coordination and patience on a global scale to fully bring life back to normal.

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