TB vaccine hopes fade

A major trial of a tuberculosis (TB) vaccine has ended in failure, marking a major setback in the fight against the disease, which cause 1.4 million deaths a year. The latest vaccine, known as MVA85A, failed to protect babies who had already had the Bacillus Calmette-Guerin (BCG), the BBC reported. BCG is only partially effective against the bacterium that causes TB, which is why several international teams are working on new vaccines. The trial, in South Africa, involved 2,794 healthy children aged four to six months, half of whom received MVA85A and the rest a placebo. They were followed up for an average of two years. The researchers found 32 cases of TB in those who had received the vaccine compared with 39 in the placebo group. This gave an effectiveness of 17 percent, which is so low as to be statistically non-significant. Designed to boost the immune responses that have been primed by the BCG vaccine, MVA85A has been undergoing human trials for more than a decade, showing it to be safe and to stimulate a high level of immune response in adults. It induced modest immune responses against TB in the infants, but these were much lower than those previously seen in adults, and were insufficient to protect against the disease, said Prof Helen McShane, from the University of Oxford, who developed the vaccine. This was the first big study in infants since BCG vaccine was introduced in 1921. Prof McShane said that the trial provided valuable information despite the setback. In an accompanying editorial Christopher Dye, of the World Health Organization (WHO), and Paul Fine, from the London School of Hygiene and Tropical Medicine, said although the results were disappointing they were "not a terminal prognosis for MVA85A, or for any of the other tuberculosis vaccines in development". The trial results were reported in the Lancet medical journal. From : ANI