The current tools are not enough to control tuberculosis epidemic. The 2009 World Health Organization (WHO) Global Tuberculosis Report says that the incidence of TB per capita continues to go down since 2004 however the decline is just one per cent per year which implies that TB will not be eliminated for centuries if we conduct 'business as usual'.
The existing BCG vaccine which came into the market in 1921, has limited effectiveness in preventing people from TB. Further, the BCG vaccine which is used to prevent childhood TB may not be safe for children living with HIV.
That is why AERAS Global TB Vaccine Foundation and other agencies including Bill & Melinda Gates Foundation are pushing hard to accelerate research and development of safe and effective TB vaccines.
Currently there are seven vaccine candidate products in different stages of the research pipeline around the world.
One phase-III clinical trial in Tanzania which was sponsored by a US University, studied adults who were living with HIV, to see if there was any reduction in disseminated TB in that population. The promising results were announced in October 2008. "We are looking at this clinical trial and might repeat the trial to get a stronger end-point," says Peg Willingham, Senior Director, External Affairs, AERAS Global TB Vaccine Foundation.
"In our research pipeline at AERAS we have six vaccine candidate products" shares Peg Willingham.
One vaccine candidate is being tested if it can replace existing BCG vaccine with a better, modern and more effective BCG vaccine. "The BCG or the improved BCG alone would be strengthened by having a booster shot - a different vaccine that will make the effect last longer and be more effective" explains Peg Willingham.
So we have five boosters and one improved BCG vaccine candidate products in the research pipeline, adds Peg.
By end of 2009, there will be 3 different clinical trials that should be entering phase IIb of two vaccine candidate products. Phase IIb is a mid-way safety and effectiveness trial between phases II and III.
"We are going to test them in different populations. Our objective is to see if the vaccine will work in people of all ages, people living with HIV, and those who have latent tuberculosis. Almost 2 billion people have latent TB so if the vaccine will not work in those with latent TB then it will take a very long time to eliminate TB" says Peg Willingham.
"Currently there are seven vaccine candidate products in different stages of clinical trials since the last 2 years, and it will be a number of years before we get to know if they are successful. They all look very safe currently and we have seen some very early preliminary results that are promising but you cannot say that a Phase I result in a few people will guarantee similar results in large scale phase III clinical trial" explains Peg Willingham.
"With sufficient resources, a new TB vaccine could be ready by 2016" says Peg Willingham.
These clinical trials are likely to be conducted at the highest international standards of ethics and quality because the product developers do aim to get the product approval by the United States Food and Drug Administration (US FDA) and such agencies in different countries around the world.
- Bobby Ramakant