Effectiveness of universal BCG immunisation in reducing the incidence and mortality of COVID-19: A secondary data analysis

Abstract

Background: The bacillus Calmette-Guérin (BCG) vaccine's immunomodulatory properties can protect against respiratory infections due to its nonspecific trained immunity of innate immune cells. The objective of the study is to assess the effectiveness of BCG in reducing the incidence and mortality of the ongoing COVID-19 pandemic.

Methodology: The present study is a secondary data analysis to compare the incidence and mortality of COVID 19 among countries that had BCG vaccine in their national immunisation schedule with other groups of countries that did not have it. Twenty-six countries with BCG vaccinations and eleven countries without BCG vaccinations were included in the analysis. The analysis was performed using the glmer() function in R and a random-effects logistic model to study the determinants of incidence and mortality.

Results: The association between the BCG vaccination and the number of cases of COVID-19 was significant in the univariate analysis (p = 0.002), upon statistical adjustment; the random effects model shows there was no association between countries with BCG vaccine included in the national immunization schedule and the number of cases (p = 0.377). Similarly, BCG was not statistically associated with mortality (case fatality rate > 5%) with a p-value of 0.443.

Conclusion: Considering single variable BCG vaccine, the incidence and mortality of COVID-19 were found to be significantly higher in non-BCG vaccinated countries while no significant association was observed when other determinants were included affecting the epidemiology of COVID-19. Additional research is recommended, to study the relationship between BCG and COVID-19.