The lower than expected number of SARS-CoV-2 cases in countries with fragile health systems is puzzling. Herein, we hypothesize that BCG vaccination policies and vaccine strain preferences adopted by different countries might influence the SARS-CoV-2 transmission patterns and/or COVID-19 associated morbidity and mortality. We also postulate that until a specific vaccine is developed, SARS-CoV-2 vulnerable populations could be immunized with BCG vaccines to attain heterologous nonspecific protection from the new coronavirus. In the lights of our investigations the most resistant countries appear to be the ones using Group I BCG strain. Within these countries, however, those who employs Russian strain is even more protected against COVID-19 infection.

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