medwireNews: The first of a series of new vaccines that have been developed to combat tuberculosis (TB) failed to show efficacy compared with placebo in South African infants, show results from a phase II trial.
"This is a very disappointing result, but this was just the first of around 12 new tuberculosis vaccines currently being tested in humans and around 50 vaccine candidates currently being tested in the lab," Richard White (London School of Hygiene and Tropical Medicine, UK), who was not involved with the research, told the press.
"It was a historic trial, the first of a new TB vaccine for nearly a century. It will lead to much valuable knowledge to help us design effective vaccines in the future," he added.
As reported in TheLancet, Michele Tameris (South African Tuberculosis Vaccine Initiative, Worcester, South Africa) and colleagues recruited 2797 infants between 2009 and 2011, aged approximately 5 months (146.2 days) on average, from the Cape Town area of South Africa to take part in their study.
The children were HIV free and had previously received the standard Bacillus Calmette-Guérin (BCG) vaccination. Overall, 1399 were allocated to receive the MVA85A vaccination and 1398 to receive placebo (Candida skin test antigen).
Over a median follow-up period of 24.6 months, 39 infants in the placebo group and 32 in the MVA85A group were diagnosed with incident TB. This translates to a rate of 1.39 versus 1.15 per 100 person years, respectively, and a vaccine efficacy of 17.3%.
Infection with Mycobacterium tuberculosis, as defined by QuantiFERON-TB Gold In-tube (QFT) conversion, was observed in 171 children in the placebo group and 178 children in the MVA85A group. This corresponds to a vaccine efficacy of -3.8%.
No major vaccine-associated adverse effects were reported, and the rate of general adverse events was similar in both groups, at 18%.
"Despite reaffirming the promising safety profile, the vaccine candidate MVA85A did not offer extra protection against TB in South African infants who had already received the BCG vaccine," said study author Helen McShane (University of Oxford, UK) in a press statement.
"The vaccine 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."
Writing in an accompanying commentary, Christopher Dye (World Health Organization, Geneva, Switzerland) and Paul Fine (London School of Hygiene and Tropical Medicine, UK) say: "Now is a key moment in tuberculosis vaccine research… If the history of tuberculosis vaccine research teaches us anything, it is to expect surprises. We need to go on playing the high-stakes game."
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