Tuberculosis Vaccine MVA85A Fails To Protect Babies in South Africa

A promising booster vaccine for tuberculosis resulted in failure after more than a decade of testing.

As TB, a contagious bacterial infection that involves the lungs, but may spread to other organs, is the leading cause of death among people with HIV in South Africa, this has created a major setback in the fight against the infection.

This was the first big study in infants since the Bacillus Calmette-Guerin (BCG) vaccine was introduced in 1921 according to NPR. 

Unfortunately, BCG proved to only be partially effective against the bacterium that causes TB, causing several international teams to work on new vaccines. The latest, known as MVA85A, unfortunately has failed to protect babies who had already had BCG.

A trial for the vaccine was conducted in South Africa, composed of 2,974 healthy children aged four to six months, half of whom received MVA85A, with the rest receiving a placebo. After two years, each participant was followed up with.

With reports from The Lancet medical journal, 32 cases of TB were found in those who had received the vaccine as compared to the 39 in the placebo group, giving an effectiveness of 17 percent, a rather small amount.

Designed to boost immune responses that have been primed by the BCG vaccine, MVA85A has been undergoing human trials for a long period, showing it to be a safe and 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," Professor Helen McShane said in a statement of the University of Oxford. She is known for developing the vaccine.

"This is the first efficacy trial of a new TB vaccine since Bacille Calmette- Guérin, a significant step in itself, and there is much that we and others can learn from the study and the data it has produced."  

Christopher Dye of the World Health Organization (WHO) and Paul Fine of the London School of Hygiene and Tropical Medicine also said in a statement that though the results were disappointing, they were "not a terminal prognosis for MVA85A, or for any of the other tuberculosis vaccines in development," adding that "now is a key moment in tuberculosis vaccine research."