No major breakthrough imminent in quest for TB vaccine

4 February 2013 - London - A vaccine candidate, MVA85A, which has been considered highly promising, has failed to confer statistically significant protection against TB disease or infection in infants who had been vaccinated at birth with Bacillus Calmette-Guerin (BCG). The results of this Phase IIb clinical trial - the first of its kind to be conducted since the BCG was introduced in 1921 - were published in The Lancet today.

The trial, which took place in South Africa and involved 2794 healthy children aged four to six months, found the vaccine was well tolerated, and there was no evidence of any harm to the trial participants. However, the researchers found an effectiveness of just 17%, which is so low as to be statistically non-significant. There were 32 cases of TB among children who had received the vaccine compared with 39 in the placebo group. The vaccine candidate also did not provide statistically significant protection from infection with Mycobacterium tuberculosis, which was a secondary efficacy endpoint.

"It is of course disappointing that this particular vaccine candidate was not efficacious, but the trial had other important outcomes. For example, as the authors note, further analysis of the data should reveal a great deal about how the body’s immune system protects against TB and what is necessary to develop an effective vaccine," said Dr Mario Raviglione, Director of the World Health Organization (WHO) Stop TB Department. "This trial also has demonstrated that it is possible to conduct a large efficacy trial among infants in an area with high TB incidence - which will provide the basis for testing other TB vaccine candidates now in the pipeline."

Funding for this clinical trial was provided by Aeras, a nonprofit biotech with a social mission to develop TB vaccines, The Wellcome Trust, and the Oxford-Emergent Tuberculosis Consortium (OETC), a joint venture between the University of Oxford and Emergent BioSolutions. This Phase IIb study was sponsored by Aeras and conducted by the University of Cape Town’s South African Tuberculosis Vaccine Initiative (SATVI). The vaccine was originally developed and investigated by the University of Oxford.

"It seems we must wait longer than we hoped to have a fully effective TB vaccine. Under these circumstances, we have to embark on research with a greater sense of urgency," said Dr Lucica Ditiu, Executive Secretary of the Stop TB Partnership. "In the meanwhile, as we continue to support and encourage research on TB vaccines, diagnostics and drugs, we should dramatically scale up our efforts to provide life-saving TB diagnosis and treatment to every person who needs it."

To read the Lancet article, click here

To link to a WHO Q&A about the vaccine trial, click here