Evidence have previously shown variation in the effectiveness of the Bacillus Calmette–Guérin (BCG) vaccine between trials, which calls into question the effectiveness of the BCG Vaccine. ACTnet's Dr James Trauer and Professor Emma McBryde recently tackled this question in a systematic review titled “Timing of Mycobacterium tuberculosis exposure explains variation in BCG effectiveness: a systematic review and meta-analysis” published in Thorax earlier this year. The focus of