Abstract

Bacille Calmette-Guérin (BCG) vaccine is part of the routine vaccination schedule in most developing countries where tuberculosis (TB) and leprosy are highly endemic. The ongoing global pandemic of COVID-19 demonstrates low levels of COVID-19 mortality / Infections ratio [of ≤ 3.2 %] in countries [Japan, India, and Brazil] that have had at least an 80-year policy of BCG vaccination of newborns. Contrarily, the top three countries [USA, Italy, and Spain], together represent > 50% of COVID-19 related infections and deaths [and death/infection ratio of ≥ 8.6%]. These countries had scattered, late, or no implementation of the BCG vaccination. Furthermore, they showed a higher rate of COVID-19 related infection [≥ 60 times], and related death [≥ 160 times] when compared to BCG vaccinating countries. Thus, given the ability of the BCG vaccine to protect adults against respiratory and various viral infections, it appears to protect against COVID-19 as well. Prior studies suggest that the trained immunity of the innate immune system may be the underlying mechanism of this BCG related protection. Socioeconomic, political, and cultural factors also contribute to the variations in COVID-19-related pandemic, infections, and deaths. The aforementioned correlation mentioned above with the BCG vaccination and COVID-19 pandemic merits reevaluation of its usage in the USA and other Western countries.

Keywords: COVID-19, BCG, Trained Immunity, Lessons learned