IFNG and tuberculosis: The importance of IFNγ has been highlighted in numerous studies8,13–16, however, the Th1 boosting candidate TB vaccine MVA85A (Modified Vaccinia virus Ankara expressing Ag85A from M. tuberculosis) failed to improve on protection afforded by BCG in vaccinated infants17; a large South African study did not find that BCG specific Th1 response correlated with risk of TB disease18; however further analysis of the MVA85A clinical trial showed that the frequencies of cells producing BCG-specific IFNγ was associated with a reduced risk of developing disease16.