On the footsteps of Hippocrates, Sanctorius and Harvey to better understand the influence of cold on the occurrence of COVID-19 in European countries in 2020

Abstract

COVID-19 pandemic has been characterized by a pattern of consecutive declines and regrowth in European countries in 2020. After being partially regressed during the summer, the reappearance of the infection during fall 2020 in many temperate countries strongly suggests that temperature and cold may play a role in influencing the infectivity and virulence of SARS-CoV-2. While promoting medicine as an art, Hippocrates interpreted with logical reasoning the occurrence of diseases such as epidemics, as a consequence of environmental factors, in particular climatic variations. During the Renaissance, Sanctorius was one of the first to perform quantitative measurements, and Harvey discovered the circulation of blood by performing experimental procedures in animals. We think that a reasoning mixing various observations, measurements and experiments is fundamental to understand how cold increases infectivity and virulence of SARS-CoV-2. By this review, we provide evidence linking cold, angiotensin-II, vasoconstriction, hypoxia and aerobic glycolysis (the Warburg effect) to explain how cold affects the epidemiology of COVID-19. Also, a low humidity increases virus transmissibility, while a warm atmosphere, a moderate airway humidity, and the production of vasodilator angiotensin 1-7 by ACE2 are less favorable to the virus entry and/or its development. The meteorological and environmental parameters impacting COVID-19 pandemic should be reintegrated into a whole perspective by taking into account the different factors influencing transmissibility, infectivity and virulence of SARS-CoV-2. To understand the modern enigma represented by COVID-19, an interdisciplinary approach is surely essential.

Corona virus disease 2019-associated liver injury in cold regions

“…During reperfusion after ischaemia, reactive oxygen species can cause a series of destructive cell responses, inflammation, and cell damage, resulting in hepatic sinusoidal endothelial cell damage, and this microcirculation disorder further aggravates hepatic ischaemia and hypoxia, thereby aggravating liver damage and creating a vicious cycle. Notably, cold accelerates the constriction of blood vessels, especially microvessels, which exacerbates inflammatory responses by inducing hypoxia and stimulating aerobic glycolysis in cells [8] .…”

“…Studies have shown that temperature may affect the infectivity and virulence of SARS-CoV-2, and a cold environment is conducive to the duplication and spread of the virus [8] . Determining the possible mechanisms and causes of liver injury is critical for making clinical decisions for the therapeutic management of COVID-19 in cold regions.…”

Patterns of the Influence of Vaccination on the Dynamics of Different Sars-Cov-2 Variants Spread. Two-Year Analysis

“…The high immunity of the population despite the spread of the Delta variant led to the suppression of the spread of SARS-CoV-2 in general [16]. However, over time, the weakening of post-infectious immunity, increasing mobility of the population and the approach of the winter period in which the pattern of human contact changes, the Delta strain has aggravated the epidemic situation [18].…”