4 February 2013

South Africa: TB Vaccine Fails

Photo: World Lung Foundation
More TB vaccines are in the pipeline (file photo).

Cape Town — A critical anti-tuberculosis (TB) candidate vaccine tried in infants, has failed in trials. The MVA85A vaccine candidate was found to be safe and well tolerated, but ineffective in combination with the Bacille Calmette Guerin (BCG), the currently used TB vaccine.

However, scientists have been quick to point out that the investigation has provided key insights. The results were published in The Lancet journal yesterday.

MVA85A was the first novel, preventive TB vaccine candidate since BCG, developed in the 1920s, to complete a Phase IIb safety and efficacy study.

The trial involved 2 797 infants. The trial vaccine was administered as a booster to the current BCG vaccine and was shown to be safe and well tolerated. However, the data showed that a single dose of MVA85A was not sufficient to confer statistically significant protection against TB disease or infection in infants who had been vaccinated at birth with BCG.

The University of Cape Town’s South African Tuberculosis Vaccine Initiative (SATVI) was a key player in conducting the trial, and it is conducting several studies of MVA85A.

The candidate vaccine is also being studied in a second Phase IIb study in HIV-infected adults in South Africa and Senegal, and a Phase IIa study in infants born to HIV-positive mothers.

“We are proud to have completed (the study) and believe the results will guide the TB vaccine field in future,” said Prof Willem Hanekom director of SATVI.

TB kills 1.4-million people every year and is increasingly resistant to existing drugs. In South Africa, a staggering half a million people develop TB every year and it is believed that an effective vaccine is the best way to try and control the epidemic.

There are currently more than a dozen other novel TB vaccines in clinical development. Most of the TB vaccine candidates in clinical development are designed to either boost BCG or improve upon it.

Aeras, a key funder in the search for a TB vaccine, said that although the results did not provide the answers hoped for, the urgency around the epidemic means “we cannot be complacent in our efforts”.

“Ten years ago, some researchers doubted the feasibility of successfully completing a study of this magnitude in a TB endemic setting. We’ve shown that a large-scale clinical trial aimed at testing a vaccine in infants can be designed and run efficiently in a setting with a high TB burden, while also adhering to the highest standards of good clinical trial practices,” Aeras said in a statement.

They added that only by doing trials such as this one can they start to tease out what protects some humans from TB and why only ten percent of those who are infected go on to develop disease.

In South Africa alone the annual cost of controlling TB cases is U$300-million.

Read The Lancet article here.

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