Epidemiological determinants of acute respiratory syndrome coronavirus-2 disease pandemic and the role of the bacille-calmette-guerin vaccine in reducing morbidity and mortality

Singh, Bhoj R.; Gandharva, Richa; Karthikeyan, R.; Singh, Shiv Varan; Yadav, Akanksha; Vinodh Kumar, O. R.; Sinha, Dharmendra K.; Jayakumar, Varsha; Dhama, Kuldeep; Kumar, Dharmender; Gandharava, Sumedha

This study analyzed the determinants of morbidity, mortality, and case fatality rate (CFR) of the ongoing pandemic of severe acute respiratory syndrome coronavirus-2 disease 2019 (COVID-19). Data for 210 countries and territories available in public domains were analyzed in relation to mandatory vaccination with Bacille-Calmette-Guerin (BCG), population density, median age of the country population, health care expenditure per capita, life expectancy at birth, healthy life expectancy, literacy rate, per capita gross domestic production adjusted to purchasing power (PPP), burden of tuberculosis (TB), acquired immunodeficiency disease caused by human immunodeficiency virus (HI V-AIDS), malaria, cardiovascular disease (CVD), neoplasm, diabetes, deaths due to energy-protein (food) deficiency (EPD), and per capita government spending on safe water and sanitation. Mandatory BCG vaccination showed a highly significant (p<0.0001) negative correlation with COVID-19 morbidity (r = -0.62) and mortality (r = -0.58) rates, but no significant correlation with CFR. The median age of the nation showed a significant (p<0.0001) positive correlation with COVID-19 morbidity (r= 0.40) and mortality (r = 0.34) rates, but no significant correlation with CFR. The pandemic resulted in higher morbidity (r= 0.47, p<0.0001) and mortality (r= 0.25, p = 0.01) rates in countries with a higher PPP than in those with a lower PPP. COVID-19 CFR and morbidity and mortality rates showed no significant correlation with population density, the burden of malaria or diabetes, or the level of spending on safe water and sanitation. Only the burden of TB showed a positive correlation with CFR (r = 0.17, p = 0.05). However, COVID-19 morbidity showed a significant (p ≤0.05) negative correlation with the burden of TB, HI V-AIDS, CVD, and EPD. Mortality and morbidity in COVID-19 patients showed a positive correlation with per capita health expenditure, life expectancy, the burden of neoplasia, and PPP.