Fig. 4.

Association of BCG-vaccination status with fatality rates and infected cases of COVID-19 among 28 countries. a Fatality rates in BCG-vaccinated (BCG+) and BCG-non-vaccinated countries (BCG−). Horizontal lines represent the means. The Student’s t test was used to evaluate statistical significance. b Correlation analysis between frequencies of S 614G variant of SARS-CoV-2 and fatality rates in BCG+ and BCG− countries. Pearson’s correlation coefficients (r) were calculated. c Number of infected cases in BCG+ and BCG− countries. Horizontal lines represent the means. The Student’s t test was used to evaluate statistical significance