Finding Tentative Causes for the reduced impact of Covid-19 on the Health Systems of poorer and developing nations: An ecological study of the effect of demographic, climatological and health-related factors on the global spread of Covid-19

Abstract

Objective - The objective of this study is to evaluate the association with different factors empirically found to affect the spread and the severity of Covid-19. Evidently there is less likelihood of having one single and absolute solution to this pandemic. It is pragmatic to look for a multi-pronged and collaborative assembly of probable solutions, which is the higher objective of this study. Design - Ecological study. Setting - Global setting including 45 countries from all six inhabited continents Population Two (2) or three (3) countries from each geographical region of the continents selected on the basis of population Main outcome - measures correlation factors derived from comparisons between different sets of variables Results - Empirical trends suggested in the existing literature were quantified in a global setting establishing clear trends. Correlation between the proportion of the population affected and median age, prime climate zones, malaria and tuberculosis incidence, BCG coverage and mitigation measures were established. Conclusions The study findings suggest that demographic and climatological factors, high endemicity of TB and Malaria, and universal BCG programmes may have a cushioning effect in the impact of Covid-19 on health systems of poorer and developing nations. In the light of these findings more emphasis is necessary on the protective effects of BCG and antiviral properties of antimalarial drugs.

Influence of Malaria Edemicity and Standardized TB Prevalence to BCG Coverage on Covid-19 Mortality

“…In this study the prevalence of mycobacterium spp. (standardized to BCG vaccine coverae) exposure of the populations is negatively associated with COVID-19 deaths per million populations, this supports the previous mentioned studies 25,26, 27,28…”

“…However, the scenario in high prevalence countries like many countries in Asia and Africa is quite the opposite where , reinfection due to contact with active cases rather than reactivation contributes to a high disease burden 24 . In May 5, 2020 latent TB infections was suggested to create heterogenous immune response to COX-COV2 viral infection in different patterns and severity according to different BCG status 27 further studies consolidate such latent TB role 28,29,30 .…”

Do low TB prevalence and lack of BCG Vaccinations Contribute to Emergence of Multisystem Inflammatory Syndrome in Children?

“…Furthermore, cross immune heterogenecity was suggested between BCG and certain viral diseases since BCG induces trained immunity through expressing heterologous antigens of different pathogens which have been developed and tested since 1991 30 . Different studies have already show statistical associations of BCG vaccinations and TB prevalence status with reduced severity of COVID-19 disease 31,32,33,34, 35 . These studies suggest that BCG and natural latent TB infection induce heterogeneous immunity against SARS-CoV2.…”

Does Latent Tuberculosis Lead to a Spurious Correlation between BCG and COVID-19 Mortality?

“…Furthermore, Sala et al, Berg Early in this pandemic, it was also suggested by a few studies that latent tuberculosis (LTB) could mitigate COVID-19 morbidity and mortality. 11,16,17,18,19,20,21, Some tested TB prevalence 16,20,22 as a proxy for LTB, while others considered LTB estimates that might cross-react with BCG and other mycobacteria. Other studies considered positivity in the TST/interferon-gamma release assay (IGRA) as a measure of the potential protective effect of the resident populations' exposure to Mycobacterium spp., whether from BCG vaccination or as a result of exposure to environmental mycobacteria.…”