Association of bacillus calmette guerin vaccine strains with COVID-19 morbidity and mortality – evaluation of global data

Background: Literature suggests that the presence of the current Bacillus Calmette Guerin (BCG) policy appears to mitigate COVID-19 disease burden but no information exists on the nature of the BCG strain and disease burden. Objectives: To study the association between type of BCG strain, BCG coverage (%), and COVID-19 disease burden. Methodology: An audit of global data on strains and disease burden was done. Country-specific data for COVID-19 cases and deaths, BCG-related data, and income level were obtained from the online databases, and the association was analyzed using linear regression. Results: Data of 139 countries were studied and 117 (84%) had a current BCG policy. Data on BCG strains were available for 51 countries and 18/51 (35%) used the Danish strain. While the choice of strain did not impact COVID-19-related disease burden, the presence of a current BCG policy was significantly associated with lower COVID-19 mortality. Conclusion: The presence of current BCG policy is associated with decreased COVID-19-related disease burden, but the type of strain used by a country in its vaccination program does not impact disease burden.