Solar ultraviolet radiation and Covid-19: is there a relationship

This question was answered by an Italian study, in press on the “Science of the Total Environment” (Link), supervised by Giancarlo Isaia, geriatrician of the Turin University and chairman of the Academy of Medicine, and by Henri Diémoz, researcher of the Regional Environmental Protection Agency (ARPA) of Aosta Valley. Moreover, other researchers from the University of Bologna, the Sapienza University of Rome, the Italian Agency for New Technologies, the Energy and Sustainable Economic Development (ENEA), the Città della Salute e della Scienza of Turin and the Environmental Protection Agencies of South Tyrol, Veneto, Piedmont and Apulia contributed to this analysis.
The study explored how some environmental factors contributed to the evolution of the ongoing COVID-19 epidemic, in addition to the well-known transmission mechanisms. The researchers have therefore examined the spatial distribution of the outbreak in Italy during the first-wave period (February-May 2020), characterised by a greater impact in northern
Italy. The investigation proved that the regional death rates and COVID-19 infections had a very significant correlation with the intensity of solar ultraviolet radiation (UV) at the Earth’s surface measured in each region by satellite and soil detection. Less significant correlations were also found with other environmental (air temperature), social (the
number of residents in Nursing Home Residences) and clinical (cardiovascular and diabetes mortality) variables.
The results of this statistical study are consistent with recently published findings, highlighting possible effects of the solar radiation on SARS-CoV-2 virus and its clinical manifestations: it is known that ultraviolet radiation can both directly inactivate the virus and increase the vitamin D levels. This latter effect could play an important role in the containment of the disease and in the lessening of its complications, thanks to the vitamin
D immunomodulatory properties. Hence, the authors suggest further investigation on the topic by means of clinical studies and they highlight the importance of having a coordinated network of UV radiation measurements in Italy.
The authors also suggest organizing campaigns to raise awareness of both the positive and the negative effects of the solar radiation. They also foster active measures to increase the vitamin D levels, either through the pharmacological supplementation, under medical supervision, or through the consumption of vitamin D rich food.
Compensating vitamin D deficiency in countries like Italy, where hypovitaminosis D is widespread, could help containing the pandemic, especially in frail elderlies, as was already suggested (Link) by Giancarlo Isaia and Enzo Medico, on behalf of the University and the Academy of Medicine of Turin