The coronovirus prefers dry cold, while it spreads less quickly in very hot and humid climates. Two Italian researchers, Francesco Ficetola and Diego Rubolini of the State University of Milan, discovered it, studying the relationships between Covid-19 cases and climatic conditions on a global scale. The results, shared on the medRxix website, raise the alert level for large regions of the southern hemisphere of the world (including South America, South Africa, Australia and New Zealand), where the pandemic could hit hardest in the coming months.
The guard must remain very high, because the SarsCoV2 virus is a particularly insidious enemy: it is in fact capable of replicating itself in the upper respiratory tract so as to be spread even by those who suffer only from mild symptoms, as shown by a study by the Charité University of Berlin published in Nature.
The more we know about the new coronavirus, however, the more it becomes possible to understand what can curb its race in the world. The climatic conditions, for example, with the variables of temperature and humidity. Milan State University researchers came to this conclusion after calculating the growth rate of Covid-19 cases in over 100 countries and macro-regions around the world. The figure was calculated on the first days of the epidemic, in order to measure the real rate of spread of the virus before the containment measures entered into force. From the crossing with the average values of temperature and humidity typical of the months of the epidemic, it emerged that the infection spreads more rapidly at average temperatures of about 5 ° C and medium-low humidity. Conversely, in very hot and humid climates characteristic of some tropical areas, the epidemic seems to run much slower, even if no populated area of the world seems to be completely unsuitable for spread.
Paradoxically, if the climate can hinder the spread of the virus, the virus in turn can jeopardize the quality of the weather forecast, also compromising the alert systems for extreme events and the study of climate change. To say this are the experts of the World Meteorological Organization (Omm), who denounce how the reduction in air traffic has already caused a sharp drop in the collection of data on weather conditions: to this could be added in the coming weeks the shortage of staff and pieces of spare part for tools maintenance.
