Reasons for optimism in the search for new vaccines for tuberculosis.

In the development of vaccines for tuberculosis (TB), the combination of the will, funding, scientific rigor, new tools, refined animal models and improved clinical trial designs are all converging at an opportune moment. The lack of optimism that has surrounded the likelihood for finding novel TB vaccines has resulted from a lack of correlates of vaccine-induced protection, a lack of tool candidate vaccines to probe the immunologic space, which may be needed, and the negative result of one recent trial. A vaccine for TB that can be delivered at a reasonable cost to the marketplace will have greater impact on the incidence of new cases of TB than any intervention in world history. Now is the time to increase resources, both financial and human intellectual capacity, for a global tuberculosis vaccine effort.