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

Abstract

Background: Regarding SARS-CoV-2 it is well known that a substantial percentage of adult population cannot get infected if exposed to this novel coronavirus. Several studies give primary indication of the possible role of preexisting immunity whether cross immunity or not. Possible role of latent TB and BCG and malaria have been already suggested to create innate cross heterogeneous immunity. We look for influence of these factors on Covid-19 mortality in malarious countries. Material and methods:80 malarious countries are enrolled in this study. Hierarchical multiple regression type of analyses is used for data analyses. TB prevalence/ 100,000 population standardized to BCG coverage rates is taken as direct factor in the test. Malaria incidence /1000 population is considered as intermediate factor and the outcome is COVID-19 mortality/ 1 million (M) population. Results: TB prevalence is associated with reduced COVID-19 mortality and malaria have an additional effect in reducing COVID-19 mortality. The results show with robust statistical support that TB prevalence was also associated with reduced COVID-19 mortality with additional effect that is also observed in TB and BCG coverage rate. Conclusions: Malaria and standardized TB prevalence are statistical significant factors predicting COVID-19 mortality in negative associations.

Low incidence of COVID-19 case severity and mortality in Africa; Could malaria co-infection provide the missing link?

“…Regarding COVID-19, it is now well known that a considerable percentage of adults are not infected even when exposed to the SARS-CoV-2, and several studies suggest preexisting immunity as the possible primary indication. Raham [ 33 ] tested this hypothesis by looking at how innate and heterogenous immunity conferred by tuberculosis (TB) and malaria influences COVID-19 incidence and mortality in malaria-endemic countries. Hierarchical multiple regression analyses for the 80 malaria-endemic countries revealed TB as the direct factor and malaria as the intermediate.…”

“…Hierarchical multiple regression analyses for the 80 malaria-endemic countries revealed TB as the direct factor and malaria as the intermediate. The results showed that, although, TB prevalence correlated to a reduction in COVID-19 mortality, an additional effect of reducing COVID-19 mortality with high significant association was observed for malaria [ 33 ]. Further evidence in support of this is adduced by report that, there is a significant positive association between malaria elimination date and COVID-19 mortality.…”

Malarial Antibodies and Endemicity: Does It Affect SARS-CoV-2 Severity and Outcomes?

“…It has been hypothesized that persons living in malaria-endemic areas acquire repeated subclinical infections and might possess immunity, which can be beneficial in mounting successful immune responses against other pathogens such as SARS-CoV-2 [22]. Though malaria influences adaptive immunity, its impact is felt more with the activation of innate immunity resulting in both trained immunity and immune tolerance, both of which are beneficial in protecting against severe malaria and may offer cross-protection against other diseases such as COVID-19 [23,24].…”

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

“…23 Regarding malaria's in uence on COVID-19 mortality, it was suggested by a few preliminary studies to reduce it. 22,26 In the context of the con icting evidence regarding BCG's signi cant correlations, the growing evidence of a role of LTB and malaria, and a lack of literature de ning LTB's confounding effect in malaria-free countries, we suggest that a confounding effect exists, as a background hypothesis for this study. This study is important at this time because several clinical trials are underway to evaluate the e cacy of BCG vaccination for COVID-19.…”

“…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.…”