Most Advanced TB Vaccine Fails to Boost Protection, Study Finds

The most advanced tuberculosis vaccine in 90 years failed to boost protection against the deadly disease when added to the shot given routinely to children, in a setback to the quest for global TB control.

In a study among 2,797 babies in South Africa, those who received the experimental MVA85A vaccine in addition to the standard Bacille Calmette-Guerin shot were no less likely to become infected with the TB bacterium or develop the disease after three years than those who only got the BCG vaccine, researchers from the University of Oxford and the University of Cape Town wrote in The Lancet journal today.

The findings deal a blow to researchers looking for a new TB vaccine to improve on BCG, which was introduced in 1921 and is only partially effective against the world’s second-biggest infectious killer.

“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,” Helen McShane, a professor of vaccinology at Oxford who developed MVA85A, said in a statement.

The study results published today will help shape the development of more than a dozen other experimental TB vaccines that are being tested worldwide, according to Aeras, the Rockville, Maryland-based non-profit organization that funded the trial.

Dormant Bug

Tuberculosis sickened about 8.7 million people in 2011 and killed 1.4 million, making it the second-deadliest infectious disease behind AIDS, according to the World Health Organization.

TB is caused by a bacterium that has infected about one-third of the world’s population, according to the Geneva-based WHO. While the bug lies dormant in most people, in about 10 percent of cases it activates, sickening its host and spreading to others through coughing and sneezing. Both the active and latent forms of TB can be cured with antibiotics, though resistance to standard drugs is increasing, according to the WHO.

In the study, 32 of the 1,399 infants who received MVA85A on top of the BCG, or 2 percent, went on to develop active tuberculosis, compared with 39 of 1,395, or 3 percent, of those who received BCG alone, McShane and colleagues wrote. The difference was not statistically significant.

Aeras is funded by the Bill and Melinda Gates Foundation, the U.K. Department for International Development, the U.S. National Institute of Allergy and Infectious Diseases, U.S. Food and Drug Administration, the Dutch Ministry of Foreign Affairs, and the Research Council of Norway.

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