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

As shown in Table 1 -A, we found a significant main effect of day, b = 0.136, p < .001, reflecting an exponential increase in cases over time. This increase was qualified by a significant interaction between day and BCG policy status. Specifically, the growth rate of COVID-19 cases was significantly slower in countries with mandated BCG vaccinations, compared to countries without mandated BCG vaccinations, b = -0.027, p < .001 (see Fig. 1 -A and B).1 This effect was not accounted for by the cultural dimensions of individualism vs. collectivism, power distance, and tightness/looseness (see Supplementary Results 1-A). Countries that once had such policies but terminated them before 2000 were not significantly different in growth rate from those that never instituted mandatory BCG vaccinations, b = -0.006, p = .440. Fig. 2 -A shows the distribution of the country-wise regression coefficients. See Supplementary Results 2-A, 3-A, and 4 for the effects of the control variables and two robustness checks.