The most promising vaccine to replace the world’s 91-year-old tuberculosis jab does not protect against the disease, according to results of large-scale trials conducted among infants in South Africa.

Doctors had high hopes for the formula, known as MVA85A, because the existing Bacille Calmette-Guérin (BCG) vaccine does not protect against pulmonary TB, a common form of the disease.

The researchers said on Monday that MVA85A was found to be safe, with no side effects, but “did not provide statistically significant protection” against the TB microbe. MVA85A was the first TB vaccine candidate to reach this stage since BCG, licensed for humans in 1921.

During the trial, which was launched in 2009, the drug was tested on 2 800 infants, who did not have TB or Aids, in the Western Cape.

All the children were given BCG at birth. Half of them also received a single dose of MVA85A at four to six months. The other half were given a placebo. They were then monitored over 37 months. Among the BCG-plus-placebo group, there were 39 cases of TB. Among the BCG-plus-MVA85A group, there were 32. The difference amounts to vaccine efficacy of just 17.3 percent.

Senior researcher Helen McShane, of the University of Oxford, said the results, published in the journal The Lancet, were disappointing but should also provide vital insights. – Sapa-AFP