Ireland's Weather Channel: Could a good summer stop the spread of coronavirus?

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Ireland's Weather Channel: Could a good summer stop the spread of coronavirus?

Viruses, such as the common winter flu, are weather dependant, according to Ireland's Weather Channel's Cathal Nolan, who suggests that a good, hot summer could help to kill off the virus - if we're lucky enough to get it.

"In a world gripped by anxiety due to the unprecedented outbreak of the Covid-19 virus, the quest for a possible vaccine is accelerating, but still remains some nine to 12 months away from being readily available on a global scale," Mr Nolan posted on his Facebook page this morning.

"In the meantime draconian but essential measures such as travel restrictions, cancelled social gatherings and social distancing are expected to become the norm. However could our weather and climate play a significant role in buying authorities and health services crucial time across the European continent?

"All viruses, especially common winter flus, are weather dependent and demonstrate seasonal variability on a hemispherical scale. Typically in the Northern Hemisphere our winter flu season commences in late November or December and persists right through until late January and into February.

"This seasonality is due in large to three key atmospheric factors which either increase or decrease the risk of transmissions. Temperatures, Absolute Humidity, and Ultraviolet Radiation. While there has been no research conducted on the impacts of Temperatures, Absolute Humidity and Ultraviolet Radiation on Covid 19 it stands to reasons that the impacts are likely to be similar in some regards to the common winter flu or other viral pathogens.

"Temperatures have a major impact on the distribution, spreadability and seasonality of the common flu and other viral pathogens. Typically colder temperatures in the range of 4-10 degrees Celsius are favourable for the spread of such viruses, which is why our winter flu season peaks between the months of December and February, during the meteorological winter calendar.

"It’s not until a rise in temperature occurring during spring that we see an appreciable decline in the rate of community/local transmission rates. The spreadability of airborne viruses is weakened considerably once temperature increase beyond 20-24 degrees Celsius, with almost no airborne transmissions occurring where temperatures exceed 30 degrees Celsius. If such variants prove to be similar with the Covid-19 outbreak then there exists a window of opportunity for European countries to limit the spread and regain control of the outbreak during the summer season.

"Likewise absolute humidity also exerts a significant impact on the spreadability of airborne viruses, with seasonal variations again being exerted. Most airborne viruses are spread via direct sneezing or coughing, with often microscopic droplets being dispersed and carried through the neighbouring environment. These droplets containing the virus spread best in cold dry air where the droplets can remain active for between 20-30 minutes according to some research papers.

"This is especially the case where absolute humidity remains below 30-40% humidity. However, when humidity levels increase above 50% humidity there is a weakening of the rate of spread, with the best results, in terms of reduced spreadability, occurring in climates where the absolute humidity is above 80%. Therefore tropical regions typically don’t experience significant outbreaks of viral epidemics, with Covid-19 favouring colder drier climates, such as those across temperate regions of the Northern Hemisphere.

"Finally, Ultraviolet Radiation also can have a limiting effect on the rate of transmissions at the local level and community level, as is demonstrated on an annual basis when dealing with the winter flu season. Viral pathogens typically affect humans during the winter months as a direct combination of reduced temperatures associated with winter, lower humidity levels due to a colder atmosphere, and finally due to biological factors including weakened immune systems due to a lack of exposure to direct sunlight and vitamin D levels.

"In simple terms, increased quantities of sunlight have an appreciable impact on our immune systems, with vitamin D helping to stave off infections as well as allowing our body to fight what viruses do lay host to our individual bodies. Therefore increase sunshine hours during the late Spring and Summer could also result in a weakening of viral transmissions and reduced mortality rates in the Northern Hemisphere.

"What this overview of meteorological conditions and Covid 19 suggests is that current social distancing and restrictive measures can play a crucial role in limiting the initial spread of the virus, which could also be enhanced due to meteorological conditions as we gradually enter our late Spring and Summer seasons. Most European nations are now in a delay phase, whereby each country wishes to minimise the rate of spread of the virus so as to ease the burden on national health services and reduce mortality rates in the elderly and those with underlying health conditions.

"If Covid 19 demonstrates similar characteristics to other winter flus and airborne viruses then meteorological and climatic factors may provide a window of opportunity during the summer months to regain control over the spread of the virus, paving the way for the development and distribution of a potential vaccine."