February 4, 2013
Vaccine Trial For Tuberculosis Fails, Researchers Still Have Hope For The Future
[ Watch the Video: Discussing New Tuberculosis Vaccine Trials ]
Lee Rannals for redOrbit.com - Your Universe Online
A new vaccine considered to be the most advanced for tuberculosis (TB) among more than a dozen now in trials has failed its study.
Researchers said they were disappointed by the results of the study, which showed that the vaccine offered little to no protection at all from TB.
Nearly 3,000 babies in South Africa took part in the study, all of whom had already been given the current Bacille Calmette-GuÃ©rin (BCG) vaccine. Half of the participants were used as a placebo group, and did not receive the new vaccination, while the other half received the trial vaccine, dubbed MVA85A.
After about two-years, the researchers found that 32 babies in the MVA85A group got tuberculosis, compared to 39 in the placebo group. The researchers said the effectiveness in infants was much lower than what had previously been tested in adults. Essentially, the very slight effectiveness makes the vaccine non-significant.
"We can look for biological signals that correlate with TB risk. We can understand more about the type and level of immune response the body needs to generate against TB," Professor Helen McShane of the University of Oxford, who developed the vaccine, said in a recent statement. "Does it just need to be a greater immune response, or a particular type, or something completely different?"
BCG was developed in 1921, and is a routine vaccination given to infants in countries that have high rates of TB. Protection from this vaccine wears off in just a few years, offering little protection from TB afterwards, so the need for a new vaccination that fights TB remains great.
The most common form of tuberculosis is transmitted through coughing and sneezing, hiding out in the cells of human hosts, making it a highly contagious bacterial infection.
Researchers wrote in the British medical journal The Lancet that if history of tuberculosis vaccine research has taught anything to researchers, it is to expect surprises.
MVA85A is not a new vaccine by any means, as it has undergone human trial testing for the past decade, so the latest results carry years of disappointments with them. However, not all is lost, according to McShane.
"This is the first efficacy trial of a new TB vaccine since Bacille Calmette-GuÃ©rin, a significant step in itself, and there is much that we and others can learn from the study and the data it has produced," McShane said in a statement.
The authors wrote in the journal that "now is a key moment in tuberculosis vaccine research," adding that, "We need to go on playing the high-stakes game."
According to the World Health Organization (WHO), about 8.7 million cases of tuberculosis pop up each year, along with 1.4 million deaths.
Dr Richard White, an epidemiologist at the London School of Hygiene & Tropical Medicine and Director of the TB Modeling and Analysis Consortium, pointed out that this was just one of 12 vaccines being tested in humans currently. He also said that it was just one of about 50 vaccine candidates currently being tested in a laboratory.
"It will lead to much valuable knowledge to help us design effective vaccines in the future," White said in a statement according to BBC News.
About $650 million has been invested into vaccine development in the past decade, versus more than $4 billion TB costs authorities to try and control the disease each year, according to WHO.
"I stand in admiration of the professionalism of this international team that understands the importance of well executed science, irrespective of the result one might have hoped for," Dr Ted Bianco, director of technology transfer at the Wellcome Trust, who have funded the vaccine's development from the start, said in the Oxford statement. "It is only through the difficult business of evaluating candidate vaccines in humans that we will really move forward in understanding how we might improve on BCG."
McShane said she remains proud of the work the team has done over the past 15 years, along with their partners.
"After all, it's only by doing this kind of trial that we can find out what does and doesn't work and eventually reach our goal," McShane said. She added that developing a TB vaccine is a "long road," but the findings from trials like this will lead to improvements in uncovering the future vaccination.