The first tuberculosis (TB) vaccine to be tested for efficacy in infants in more than 40 years has proved ineffective as a TB booster shot, but it may have laid the groundwork for the next phase in TB vaccine research.
The world has relied on the Bacille Calmette-Guerin (BCG) vaccine against TB for over 90 years, despite recent controversy over its efficacy. In clinical trials, effectiveness estimates have ranged from 80 percent protection to none at all; the reasons for these differences are not yet understood.
Researchers from the South Africa TB Vaccine Initiative (SATVI), Oxford University and Aeras, a non-profit organization working on TB vaccines, were hoping a recent trial in South Africa’s Western Cape Province would change all that. They tested a new TB vaccine booster, known as MVA85A, in almost 2,800 BCG-vaccinated infants between the ages of four and six months.
While the two-year trial confirmed the vaccine was safe for use in infants, MVA85A was shown to be ineffective, meaning that it provided no additional protection to the babies who received it, according to results published online in The Lancet on 4 February.