Status of vaccine research and development of vaccines for tuberculosis.

TB is now the single pathogen that causes the greatest mortality in the world, at over 1.6 million deaths each year. The widely used the 90 year old BCG vaccine appears to have minimal impact on the worldwide incidence despite some efficacy in infants. Novel vaccine development has accelerated in the past 15 years, with 15 candidates entering human trials; two vaccines are now in large-scale efficacy studies. Modeling by three groups has consistently shown that mass vaccination that includes activity in the latently infected population, especially adolescents and young adults, will likely have the largest impact on new disease transmission. At present the field requires better validated animal models, better understanding of a correlate of immunity, new cost-effective approaches to Proof of Concept trials, and increased appreciation by the public health and scientific community for the size of the problem and the need for a vaccine. Such a vaccine is likely to also play a role in the era of increasing antibiotic resistance. Ongoing efforts and studies are working to implement these needs over the next 5 years, which will lead to an understanding that will increase the likelihood of a successful TB vaccine.