A new vaccine developed by scientists in the UK has failed to protect infants against tuberculosis, a late stage clinical trial has shown.

MVA85A, the world’s most advanced of more than a dozen TB vaccines now in clinical trials, was designed to improve immune responses from the only licensed TB vaccine, Bacille Calmette-Guérin, which is widely used in newborns.

But data published in the Lancet shows that a single dose of MVA85A, developed by researchers at Oxford University, is not sufficient to "confer statistically significant protection against TB or infection in infants who had been vaccinated at birth with BCG."

The phase IIb study enrolled nearly 2,800 infants in South Africa who had received BCG at birth between 2009 and 2011.

Around 93% of infants enrolled completed the study, half of whom received the MVA85A while the other half received a placebo, and were monitored for three years for signs of TB.

There were 32 cases of the disease in the infants that received BCG plus MVA85A compared with 39 cases of disease among those receiving BCG and a placebo. Non-significant vaccine efficacy was measured at 17.3% at study completion.

Professor Helen McShane, the original developer of the vaccine, said that although the results of the efficacy trial are not what her team had hoped for, further analysis of the data should reveal what is necessary to develop an effective vaccine.

"The difficulty of this task is one reason why there has not been a new TB vaccine since BCG was developed more than 90 years ago, but one is still urgently needed and I’m not about to give up now."

Funding for the clinical trial was provided by Aeras, a nonprofit biotech, the Wellcome Trust, and the Oxford-Emergent Tuberculosis Consortium (OETC), a joint venture between the University of Oxford and Emergent BioSolutions.

Image: TB effects an estimated two billion people around the world.