Science Speaks is live-blogging from IDWEEK 2013. Meeting in San Francisco from Oct. 2-6, with the theme “Advancing Science, Improving Care,” the conference features breaking scientific advances and approaches in prevention, diagnosis, treatment, and epidemiology of infectious diseases, including HIV and TB.
SAN FRANCISCO, Calif — Willem Hanekom from the University of Cape Town updated IDWeek attendees about the progress of TB vaccine development on Thursday in San Francisco. He argued for an initial focus on HIV-uninfected adults and adolescents in vaccine efforts and noted that a TB vaccine should be viewed in the context of a comprehensive response to tuberculosis, not in isolation.
There now are 14 vaccine candidates in clinical development and more than that in pre-clinical efforts. “We are learning, but there is no magic bullet yet,” according to Hanekom. Since the mechanism that protects individuals from developing TB disease is not yet known, TB vaccine developers are forced to engage in lengthy and expensive clinical trials to evaluate potential vaccine candidates.
But they are looking for other ways to evaluate effectiveness that do not require as large numbers of trial participants and as much time. For instance, since it is known that 5 percent of individuals who successfully complete TB treatment and are deemed “cured” will in fact go on to develop TB disease again within a year after treatment, researchers are exploring whether they can look at a vaccine’s effectiveness in preventing recurrent TB disease in a group that has successfully completed treatment. This evaluation requires a much smaller sample size although there is no certainty the outcome is relevant. Researchers are also looking at whether they can evaluate vaccine candidates by looking at the acquisition of TB infection in adolescents. In South Africa, 60 percent of young people will become infected with tuberculosis by age 18. It may be possible to evaluate the efficacy of a vaccine by looking at its ability to prevent TB infection in adolescents.
Research efforts are still underway to understand the host or patient response. What about an individual‘s biology make them more or less likely to develop TB disease? While we know that HIV infection is a significant risk factor as are other conditions that undermine the immune system, more generalizable answers to that question remain elusive.