New Vaccines Targeting Adults Could Help Eradicate Tuberculosis

By C. Rajan, contributing writer

A new study indicates that vaccines targeting teens and adults can help eliminate tuberculosis (TB) more effectively than the present TB vaccine for infants, according to a recent report in the University Herald.

TB is a highly contagious bacterial infection which mostly affects young adults. According to the World Health Organization (WHO) estimates, there were approximately 8.6 million new TB cases and 1.3 million TB deaths in 2012. Without effective treatment, the disease has a high mortality rate. Due to the immense global burden of this disease, the WHO has set its sights on eliminating TB by 2050.

In this recent study, researchers from the London School of Hygiene & Tropical Medicine and the Stop TB Department at the World Health Organization found that the goal of eradicating TB by 2050 could be met if new vaccines were developed for adolescents and adults. The researchers used a mathematical model to identify which vaccination strategy would have the greatest impact on TB worldwide from 2024 to 2050, assuming new vaccines will be in the market by 2024.

The researchers say that a new vaccine for adults would be more cost-effective and have a greater impact on tackling TB, regardless of low efficacy or the vaccine’s shorter duration.

"Dramatic levels of control are needed to eliminate TB and new vaccines need to be developed now," said Gwen Knight, lead author of the study and research fellow in infectious disease modeling. "But because trials of TB vaccines are hugely expensive, their development needs very clear guidance. If elimination by 2050 is the goal, our study provides evidence that new vaccines should focus on targeting adolescents and adults rather than children."

The current vaccine, bacille Calmette-Guérin (BCG) is the most widely used TB vaccine for children worldwide. The BCG vaccine is effective in preventing children up to age 15 from developing the disease, however it does not prevent infection. Thus, children can become infected with TB and then develop the disease as adults, despite extensive childhood vaccination programs.

While there are approved drugs available to treat infected persons, currently there is no approved TB vaccine for teens and adults, so their risk of developing TB remains high.

Development of new vaccines is a much more rigorous and time-consuming process than new drugs, so the new study points the research direction towards TB vaccines for adults.

There are several new vaccines in development that are targeted towards adolescents and adults. GSK’s novel TB vaccine, M72/ASO 1E, is currently in a Phase 2 clinical trial, where it will be tested on more than 3,500 healthy adults in South Africa, Kenya, and Zambia over the course of the next four years, iOL scitech reports. If the vaccine is found to be effective, then it can be used as a booster to the BCG vaccine.

Also, in January, Danish scientists reported that they had developed a new type of TB vaccine for adults which showed promising results in mice models. This vaccine consists of a mixture of proteins and works through an entirely different mechanism than the BCG vaccine. According to the researchers, the vaccine teaches the immune system to recognize essential proteins in the tuberculosis bacterium so that the body’s defense system can attack the infection.