Abstract
BackgroundTo investigate the association between parameters indicating immunity from BCG at country level (presence of BCG vaccination policy, BCG coverage, age-specific incidence of tuberculosis (TB)) and the morbidity and mortality of COVID-19.MethodsCountry-specific data for COVID-19 cases and deaths, demographic details, BCG coverage and policy, age-specific TB incidence and income level were obtained. The crude COVID-19 cases and deaths per 100,000 population were calculated and assessed against the parameters indicating immunity from BCG using linear regression analysis.ResultsUnivariate analysis identified higher income level of a country to be significantly associated with COVID-19 cases (p < 0.0001) and deaths (p < 0.0001) but not with its case fatality rate. The association between COVID-19 and TB was strongest for TB incidence in patients > 65-years (Cases (rs = − 0.785,p = 0.0001)) and deaths (rs = − 0.647,p = 0.0001).Multivariate analysis identified the higher income level of a country and not having a universal BCG vaccination policy to affect the COVID-19 cases. The deaths were inversely affected by the presence of BCG vaccination policy and coverage; and positively by the TB incidence in patients > 65-years.ConclusionSignificant inverse correlations observed between cases and deaths of COVID-19 and BCG related parameters highlights immunity from BCG as a likely explanation for the variation in COVID-19 across countries.
Highlights
The COVID-19 outbreak started in December 2019 in Wuhan Province, China [1] and has spread to six continents
Bacillus Calmette–Guérin (BCG) is a live-attenuated vaccine primarily developed to protect against childhood meningitis and disseminated tuberculosis (TB) [3]
Distribution of COVID-19 cases and deaths by income level of countries The COVID-19 cases were significantly different between countries of different income levels (Kruskal-Wallis test, p < 0.0001) (Fig. 1)
Summary
The COVID-19 outbreak started in December 2019 in Wuhan Province, China [1] and has spread to six continents. It is caused by SARS-CoV-2 [2]. It has overwhelmed the health system capacity in many countries. The World Health Organization (WHO) recommends BCG vaccination at birth in countries with both universal and selective vaccination policies [4]. To investigate the association between parameters indicating immunity from BCG at country level (presence of BCG vaccination policy, BCG coverage, age-specific incidence of tuberculosis (TB)) and the morbidity and mortality of COVID-19
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