Does TB Vaccination Reduce COVID-19 Infection?: No Evidence from a Regression Discontinuity and Difference-in-Differences Analysis

Abstract In the middle of the global COVID-19 pandemic, the BCG hypothesis, the prevalence and severity of the COVID-19 outbreak seems to be negatively correlated with whether a country has a universal coverage of pediatric Bacillus Calmette–Guérin (BCG) vaccination, has emerged and attracted the attention of scientific community and media outlets. However, all existing claims are based on cross-country correlations that do not exclude the possibility of spurious correlation. By merging country-age-level confirmed case statistics of COVID-19 from 17 countries with the start/termination years of pediatric universal BCG vaccination policy and age-specific BCG vaccination coverage, this paper examines the role of BCG vaccination in COVID-19 infection. Despite the cross-country evidence from the previous literature, the results of both regression discontinuity design and difference-in-differences approaches do not support the BCG hypothesis.The results of these previous studies are likely to suffer from spurious correlations.