Protecting children against tuberculosis (TB) in developing countries may become easier as a result of South African-based research that has found that a simple vaccination technique is as effective as the more complicated method currently recommended.
An international team of researchers working through the University of Cape Town and the South African Tuberculosis Vaccine Initiative (Satvi) compared two methods of giving the Bacille Calmette-Guerin (BCG) vaccination to 11Â 682 newborn children in the Boland-Overberg area of the Western Cape. This region has the highest rates of TB in South Africa which, in turn, has one of the highest rates of TB infection in the world.
The percutaneous method involves smearing the vaccine on the child’s skin and then using a tool with multiple small needles to push the vaccine into the skin. This is the older technique and has largely been replaced by the World Health Organisation-endorsed (WHO) intradermal method, which uses a hypodermic needle to inject the vaccine into the skin, but not through it into the tissues below.
The newer technique is cheaper because needles are less expensive than percutaneous vaccine tools, and it also allows an exact dose to be given. But the intradermal method requires much more skill on the part of the healthcare workers to hold the needle in the thin layer of skin, especially if the recipient is a tiny and uncooperative baby.
The Western Cape study was coordinated and funded by the Aeras Global TB Vaccine Foundation, a United States-based NGO which focuses on developing TB vaccinations. Aeras senior director Dr Lawrence Geiter this week presented the South African Department of Health with the trial results, showing that the two techniques are equivalent in efficacy and safety.
Dr Geiter says the researchers will now approach the WHO and other bodies to amend the international guidelines so that countries can choose the technique that best suits their circumstances.
Because the percutaneous method is more easily taught, this could have an important impact on developing countries which have a shortage of trained healthcare workers. Giving governments the choice of method should also make it easier for them to find the funding and to band together to enjoy economies of scale when buying the percutaneous vaccines and tools, driving down the price and luring more manufacturers into the market. At the moment there is only one commercial supplier of the percutaneous vaccine.
One of the benefits of the trial is that, using funding from the Bill and Melinda Gates Foundation, Aeras and its Satvi partners have developed a clinical research network in the Western Cape which can be used for future vaccine studies.
A new TB vaccine is urgently needed because the BCG provides only imperfect protection. Developed in the 1880s it is known to protect children against some of the more damaging forms of TB such as TB meningitis. However, it doesn’t protect effectively against pulmonary TB and it is thought that its protective effects wear off before adulthood. In the Boland-Overberg study, 6% of the children participating developed known or strongly suspected active TB within their first two years of life, despite having been vaccinated.
Aeras has developed six potential vaccines which are starting clinical trials at the moment and hopes to start testing in South Africa early next year once preliminary trials in the US have been completed and the ethical and regulatory requirements have been cleared.
“The capacity to do large complex trials of new TB vaccines has been clearly demonstrated in South Africa and this is likely the only place in the world that a phase III [large scale efficacy tests involving thousands of people] of a new TB vaccine could be done at the present time,” says Geiter.