TB infection and BCG vaccination: Are we protected from COVID-19?

Madan, Manu; Pahuja, Sourabh; Mohan, Anant; Pandey, Ravindra Mohan; Madan, Karan; Hadda, Vijay; Tiwari, Pawan; Mittal, Saurabh

Abstract Objectives The incidence of emerging COVID-19 disease is variable across the different parts of the world. Apart from travel patterns, other factors determining this difference may include host immune response. Aim of this study was to assess the effect of TB endemicity and BCG coverage on COVID-19. Study design Cross sectional study. Methods We reviewed available data regarding tuberculosis incidence, BCG coverage (as per WHO), and COVID-19 incidence of 174 countries. We divided the countries into four cohorts depending upon annual TB incidence and BCG coverage. Results Countries with high TB incidence had lower COVID-19 as compared to countries with low TB incidence. Similarly, countries with high BCG coverage had lower incidence of COVID-19 suggesting some protective mechanisms in TB endemic areas. Although, the ecological differences and different testing strategies between countries could not be accounted for in this analysis. Conclusion Higher TB incidence and BCG coverage were found to be associated with lesser incidence of COVID-19. This outcome paves the way for further research into pathogenesis and immune response in COVID-19.