The Stop TB Partnership has the aim of eliminating tuberculosis by 2050. It will need effective vaccination. BCG protects against disseminated tuberculosis in young children but is relatively ineffective in combating the spread of tuberculosis in high prevalence countries such as South Africa. At present 12 new vaccines are being assessed in clinical trials. One, MVA85A, is a recombinant strain of modified vaccine Ankara virus expressing the immunodominant Mycobacterium tuberculosis protein, antigen 85A, and is intended to boost the effectiveness of BCG. Now a trial of MVA85A for infants in South Africa (Lancet 2013;381:1021–8; see also comment ibid 972–4) has given disappointing results. It included 2797 HIV negative infants aged 4–6 months who had previously been given BCG and who were randomised to a single intradermal dose of MVA85A or placebo (Candida skin test antigen). The incidence of tuberculosis, using microbiological, radiological and clinical criteria, over a median follow-up of 24.6 months was 32/1399 (2.3%, 1.15 per 100 child years) in the MVA85A group and 39/1395 (2.8%, 1.39 per 100 child years) in the control group. Mycobacterium tuberculosis infection (conversion on the Quanti FERON—TB Gold In-tube test) occurred 13% …