The major stumbling blocks in TB vaccine development to date have been the lack of an immunological correlate of protection, the reality that protection in preclinical challenge models does not reflect field efficacy data, and, in this context, the need for a human challenge model to help rationalise selection of candidates to proceed to efficacy studies. Continued research in these areas is critical to facilitate and de-risk vaccine product development and is proceeding in parallel to advancing candidates in the clinic.