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Hot and humid weather can slow COVID-19 transmission, new study finds

Published on 26/05/20 at 12:09pm
Photo by Brianbatesd at English Wikipedia

A new study from the Massachusetts Institute of Technology, Harvard, Virginia Tech and the University of Connecticut has shown that hot and humid weather slows coronavirus transmission.

The research showed that there was about a 1.7% reduction in transmission risk per degree Fahrenheit once temperatures rose above 25°C/77°F. COVID-19’s reproduction increased 0.8% for each additional millibar of air pressure above 1016 millibars.

In the context of America, this means somewhere like New Orleans can expect fewer incidents during the summer, followed by a steep increase in the autumn, whereas somewhere which is cooler and damper, like Seattle, will have a steadier stream of cases throughout the year.

In the study, Wind speed also affected the spread of the virus with an increase of one standard deviation in wind speed resulting in a 3.8% increase in the virus’s reproduction rate. Snow increased this by 1.4% while rain increased it by 2.9%.

Hazhir Rahmandad, associate professor of system dynamics, MIT Sloan School of Management, told BioSpace, that when compared with influenza: “The main difference is that baseline transmission rates for flu are relatively lower because a larger percentage of the population has had the flu and is immune. Therefore, the reproduction number for influenza is smaller than for COVID-19.”

This research follows a similar study being carried out at the Lawrence Berkeley National Laboratory , which will apply machine learning methods to map the severity, distribution and duration of the COVID-19 pandemic.

Researchers have already indicated that the geographical differences may have an impact on the rates of transmission. Temperature, humidity and the UX index have all been associated with the rates of COVID-19, while human contact still remains as the dominant influence on the spread of the virus. For example, in the southern hemisphere the spread of the disease has been slower, and places like India do not seem to have the same rate of spread as northern hemisphere countries.

Conor Kavanagh

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