Mandated Bacillus Calmette-Guérin (BCG) vaccination predicts flattened curves for the spread of COVID-19

Martha K Berg; Qinggang Yu; Cristina E Salvador; Irene Melani; Shinobu Kitayama

Since vaccination may become effective at the population level only when a vast majority is made resistant against a target virus, a phenomenon known as "herd immunity" (13), we first tested whether the growth curves would be significantly less steep in countries that have continued to mandate BCG vaccination at least until very recently, as compared to countries that do not currently require it. We then explored whether there might be any difference between those that never had such a policy and those that had one during the 20th century but have since terminated the policy for at least a few decades. Lastly, we tested whether the groups of the countries that vary in the BCG policy status might vary on various cultural dimensions, such as individualism vs. collectivism (13, 14) and the tightness vs. looseness of social norms (14) .