Lower COVID-19 mortality in Italian forested areas suggests immunoprotection by Mediterranean plants

Abstract

The COVID-19 pandemic has induced dramatic effects on the population of the industrialized north of Italy, whereas it has not heavily affected inhabitants of the southern regions. This might be explained in part by human exposure to high levels of fine particulate matter (PM) in the air of northern Italy, thus exacerbating the mortality. Since trees mitigate air pollution by intercepting PM onto plant surfaces and bolster the human immune system by emitting bioactive volatile organic compounds (VOCs), we hypothesize a protective role of evergreen forested areas in southern Italy. We compared the mortality rate due to COVID-19, the death number, the positivity rate and the forest coverage per capita in various Italian regions. Hectares of forest per capita and prevalence of deciduous versus evergreen forestal species were also estimated. In silico docking studies of potentially protective compounds found in Laurus nobilis L., a typical Mediterranean plant, were performed to search for potential antivirals. We found that the pandemic's severity was generally lower in southern regions, especially those with more than 0.3 hectares of forest per capita. The lowest mortality rates were found in southern Italy, mainly in regions like Molise (0.007%) and Basilicata (0.005%) where the forest per capita ratio is higher than 0.5 Ha/person. Our findings suggest that evergreen Mediterranean forests and shrubland plants could have protected the southern population by emission of immunomodulating VOCs and provision of dietary sources of bioactive compounds. Moreover, in silico studies revealed a potential anti-COVID-19 activity in laurusides, which are unexplored glycosides from bay laurel. Overall, our results highlight the importance of nature conservation and applications to the search for natural antivirals.

Air pollution by NO2 and PM2.5 explains COVID-19 infection severity by overexpression of angiotensin-converting enzyme 2 in respiratory cells: a review

“…Air pollution also acts as the route for much other secondary diseases and associated deaths (Walker 2020). Lower COVID-19 mortality in forested areas reinforces the influence of air pollution and suggests immunoprotection by Mediterranean plants (Roviello and Roviello 2020). Death rates under air pollution-related diseases and associated complications are at least 100-folds more in poor countries in comparison to the countries with high income.…”

How human thermal plume influences near-human transport of respiratory droplets and airborne particles: a review

“…Further, recent studies indicated that high concentrations of aerosol particles could significantly increase the susceptibility of COVID-19 infection and symptom aggravation in infected individuals (Accarino et al 2020 ; Fattorini et al 2020 ; Roviello et al 2020 ; Travaglio et al 2020 ). A known contributing factor is that airborne particles are capable of harboring pathogens by forming clusters with droplets and droplet nuclei and facilitate their long-distance transport (Alonso et al 2014 ; Zhao et al 2019 ).…”

Who is running faster, the virus or the vaccine?

“…Before scientists find a perfect cure for treating infections by the novel coronavirus, vaccinating the global population will be the keystone in the current battle against COVID-19 (Stern 2020;Williams et al 2020). The numerous challenges in the lab-to-jab process not only present a daunting task, but also provide an unprecedented opportunity to collaborating and finding innovative solutions, on a global scale and across different disciplines to increase the preparedness of our communities for future pandemics (Paital and Agrawal 2020;Roviello and Roviello 2020;Sharma et al 2020;Wang et al 2020d). Since epidemics and pandemics may emerge in a not too distant future, these experiences will become an important part of the legacy of the COVID-19 era.…”