TB Prevalence Influence on Covid-19 Mortality

Abstract

Back ground : Latent TB disease reflect a state of persistent immune response to stimulation by Mycobacterium tuberculois . TB infection lead to latent TB disease in 90-95 % while 5-10 % of individuals develop active TB disease when compared to BCG , BCG is 60% effective against the development of active TB. Studies done to test association of BCG with covid-19 morbidity and mortality and it was thought that BCG have preventive effects due to presumed non specific anti viral effects in this study we test association between prevalent of TB which reflects about 90-95 % of corresponding latent TB infection with covid 19 mortality. Materials and methods : countries divided into 5 groups according to BCG following status : No vaccination at all no previous BCG group , no current but had BCG in past (one or more), 1 current BCG with previous booster (s) , just 1 BCG now no previous booster (s) and more than 1 BCG setting now. covid -19 deaths taken as it is on these are tested against TB prevalence 2018. Results: Slop values have significant influences between TB prevalence and covid -19 deaths among all tested groups and are reversed in just 1 BCG now no previous booster (s) groupP<0.01 coefficient (0.30751) ,1 current BCG with previous booster (s) P<0.01 coefficient (0.63662) , and more than 1 BCG setting now group P<0.05 with coefficient of (0.61580). While no vaccination at all no previous BCG group shows Compound model linear regression P<0.05 coefficient ( 97.45%)and No current but had BCG in past (one or more) group shows Cubic model P<0.01, coefficient (66.098%)The overall slope value is highly significant and reverse influence at P<0.01, as well as highly significant relationship coefficient (0.36749). The linear regression model obtained in logarithmic mode for all tested sample and being inverse in countries with more than 1 BCG setting at this time and countries with 1 current BCG with previous booster (s) furthermore linear regression model is logarithmic in countries with just 1 BCG now and no previous booster (s) . Introduction:About one-quarter of the world's population may be infected with latent tuberculosis 1 which is defined as a state of persistent immune response to stimulation by Mycobacterium tuberculosis antigens with no evidence of clinically manifest active TB 2 . It is estimated that the lifetime risk of an individual with LTBI for progression to active TB is 5-10% 3 , furthermore more than 90% of people infected with M. tuberculosis for more than two years never develop tuberculosis even if their immune system is severely suppressed 4 ,while BCG is highly efficacious at preventing meningeal and miliary TB, but is at best 60% effective against the development of pulmonary TB in adults and wanes with age. 5 It is hypothesized that beneficial heterologous non-specific effects and innate immune memory training through epigenetic reprogramming. 5 , 6 Furthermore secretion of pro-inflammatory cytokines, specifically IL-1B play a vital role in antiviral immunity this is believed to be increased b...

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

“…In this study the prevalence of mycobacterium spp. (including BCG vaccine) exposure of the populations is negatively associated with COVID-19 deaths per million populations this supports the previous mentioned studies 27,28,29,30 .…”

BCG Correlation with Latent Tuberculosis Can Lead to Spurious Correlation with Reduced COVID-19 Mortality

“…Furthermore, Sala et al [7], Berg et al [8] Dayal et al [9] Akiyama et al [10], Green et al [11] Hegarty et al [12] , Shet et al [13], Ozdemir et al [14] and, more recently, Brooks et al [15] showed significant correlations between BCG and COVID-19 mortality. Early in this pandemic, it was also suggested by a few studies that latent tuberculosis (LTB) could mitigate COVID-19 morbidity and mortality [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.…”

“…Early in this pandemic, it was also suggested by a few studies that latent tuberculosis (LTB) could mitigate COVID-19 morbidity and mortality [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 [17,18,23].…”

“…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 [17,18,23]. Raham TF and Al-Momen H. et al shed light on the effectiveness of TB prevalence as a proxy for LTB, according to different BCG groups bypassing the BCG effect [16,20].…”

Tuberculosis prevalence relation to COVID-19: mortality in malaria free countries

“…These studies suggested heterogeneous immune response to COX-COV2 viral infection. [10][11][12][13] Despite this significant association, some countries are hugely disparate case fatality rates among low% LTBI countries. 14 Also, disparity exists in case fatality rates among high %LTBI countries.…”