Key TB vaccine trial fails; more waiting in the wings

CHICAGO (Reuters) – A highly anticipated study of the first new tuberculosis vaccine in 90 years showed it offered no added benefit over the current vaccine when it came to protecting babies from TB infections, a disappointing but not entirely unexpected outcome, researchers said on Monday.

The vaccine, known as MVA85A, is the most advanced of more than a dozen TB vaccines now in clinical trials in people, and scientists are poring over the results to learn why the trial failed and how the results can inform future studies.

MVA85A was developed by researchers at the University of Oxford in Britain with support from Aeras, the Wellcome Trust, the European Commission and the Oxford-Emergent Tuberculosis Consortium, a joint venture between Oxford and Emergent Biosolutions Inc.

“Obviously, we all would have liked to see greater protection,” said Dr Ann Ginsberg of Aeras, a non-profit biotech based in Rockville, Maryland and funded in large part by the Bill & Melinda Gates Foundation.

The current TB vaccine, known as Bacille Calmette-Guérin, or BCG, was developed in 1921, and is given routinely to babies in countries with high rates of TB to prevent severe disease.

However, protection wears off in just a few years, and BCG does nothing to protect against the most common form of tuberculosis that invades the lungs of adults and adolescents, and can be transmitted through coughing and sneezing.

For the study in the British medical journal, the Lancet, researchers tested the vaccine in nearly 3,000 healthy babies in South Africa who had already been given the BCG vaccine. Half also got the new vaccine and half served as the placebo group.

After a follow-up period of about two years, 32 babies in the MVA85A group got TB compared with 39 in the placebo group, a modest, but statistically insignificant improvement.

Researchers said the protection seen in the infants was much lower than had been seen in adults who had tested the vaccine, and they plan to look more closely to understand why. They did not provide figures on how well it worked for adults.[Source]

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