The impact of the global distribution of bats on mortality in COVID-19 patients

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) originated in November 2019 in China and quickly spread throughout the world causing a disease named COVID-19. An analysis of the epidemiological data on morbidity and mortality caused by SARS-CoV-2 shows that, in some countries, namely Belgium, UK, France, Italy, the Netherlands, and Spain, an increased case fatality rate (CFR) was noticed compared to the rest of the world. The CFR, calculated as the number of deaths from the total number of the cases, ranges in these countries from 10.22% to 15.8% according to the Center for Evidence-Based Medicine (CEBM). At the same time, in the countries of Central and Northern Europe, this parameter varies between 3.78% and 4.94%. This significant heterogeneity in CFR between countries has not been given a convincing explanation yet. It was found that the precursor of SARS-CoV-2 is a virus circulating in bats in China. The mutations that occurred in this virus altered its receptor specificity, thereby enabling viral infection in humans. Bats are highly resistant to viral infections due to their robust interferon system and a reduced level of inflammatory reactions. Viruses replicate in these animals up to high titers without any substantial harm to their health. As a result, bats represent a large reservoir of viruses with the potential to infect other animals, including humans. The infection of people with bat (or human) betacoronaviruses can lead to the formation of memory B-cells that provide an accelerated antibody response to cross-reactive epitopes upon subsequent infection. The early emergence of neutralizing antibodies in SARS-CoV-2 patients correlates with the severity of the disease and the likelihood of a fatal outcome. The antibody-dependent enhancement (ADE) of infection/disease known for various viruses, including SARS-CoV-1 and MERS-CoV, may be a possible cause of this phenomenon. In this article, we suggest a close connection between the distribution areas of bats carrying SARS-CoV-1-like viruses and the CFR from COVID-19.