Currently to assess vaccine efficacy against TB there is no reliable alternative to large, randomized controlled trials. These efficacy trials for novel TB vaccines are challenging, time consuming and very costly. For other diseases, such as malaria, challenge studies have been informative. The development of a safe controlled human mycobacterial challenge model which would ultimately be validated against field efficacy studies could greatly facilitate TB vaccine development by being a guide for selecting which candidate TB vaccines to take forwards to large efficacy trials.