Regional BCG vaccination policy in former East- and West Germany may impact on both severity of SARS-CoV-2 and incidence of childhood leukemia.

We read with great interest the recent thorough study from Miller et al. [1], who reported a beneficial impact of early Bacillus Calmette–Guerin (BCG) vaccination, and linked morbidity and mortality due to SARS-CoV-2 with BCG vaccination policy. They found that countries without policies of universal BCG vaccination (like Italy, the Netherlands, or the United States) have been more severely affected compared with countries with universal and long-standing BCG policies. Since senior citizens are particularly sensitive to COVID-19, newborn vaccination programs implemented in the 1940s and 1950s should be the most beneficial. Thus, we were impressed by the linear correlation between the year of the establishment of universal BCG vaccination and the mortality rate presented by Miller et al. [1]. In our view, this is a convincing argument for the hypothesis that the earlier the vaccination policy was established, the larger the segment of the elderly population being protected.