Relación entre la vacunación BCG y el incremento de la mortalidad por COVID-19. ¿Falacia ecológica?

Ecological studies are one of the most common study designs used to establish the association between certain factors and disease development. However, they have limitations mainly on how to measure the variables, so their results must be verified in studies with greater validity. Therefore, the study that links the possible relationship between higher mortality from COVID-19 and non-vaccination by bacillus Calmette-Guérin (BCG) that was recently published, remains in doubt due to the lack of rigor in the methodology used. [ABSTRACT FROM AUTHOR]