COVID-19 LOWER CASE FATALITY RATE IN THE HIGH ALTITUDES CITIES OF BOLIVIA, COLOMBIA, ECUADOR, MEXICO, AND PERU: POSSIBLE PHYSIOLOGICAL AND ENVIRONMENTAL CAUSES

Abstract

The COVID-19 worldwide public health breakout resulted in a historical research race. Medical research and practice at high altitude provided us with a unique perspective for the understanding of hypoxia in this disease. Popular belief stated that living under chronic hypobaric hypoxia would be correlated with higher COVID-19 severity. Previous studies from our team and others suggested a lower COVID-19 incidence in high altitude populations. Later, mortality became the focus of analysis. An analytic, retrospective, comparative multi-national study was carried out from the beginning of the pandemic until the end of 2020. Official open sources from Bolivia, Peru, Colombia, Ecuador, and Mexico were used to access the COVID-19 Case Fatality Rate (CFR) difference between the highland municipalities (or sample) (>2,500 m) compared to the lowland municipalities (or control) (< 1,000 m) in each country.
Data analysis included statistical tables regarding the population, total positive cases, recovered cases, and deaths. Chi-square test, Odds ratio, Spearman correlations, and Post Hoc analysis were performed. Lower CFR was statistically significant in the highlands compared to the lowlands in all countries. The possible explanations that could explain this COVID-19 protective behavior at high altitudes are physiologic and environmental (physics). The physiologic include higher hemoglobin levels, erythropoietin levels, greater immunity, lower carbon dioxide levels, lower incidence of asthma, and a lower number of ACE2 receptors in high-altitude inhabitants. The environmental include higher Ultra-Violet radiation, lower molecular density in the atmosphere, and lower humidity.