New TB Vaccine Clears First Hurdle

The first new TB vaccine for more than 80 years has successfully come through safety trials in the UK.

The sub-unit* prophylactic vaccine, devised by a team from Oxford University led by Dr Helen McShane, is designed to be used in tandem with the tried and tested BCG inoculation -- first introduced in 1921 -- and not to replace it.

TB has been around since the time of the pharaohs and kills some 2m people worldwide annually. In England the number of cases has risen by 25 percent over the last decade. Earlier this month the chief medical officer, Sir Liam Donaldson, announced new measures to try and eliminate the disease which claims about 350 lives a year in this country.**

According to the World Health Organization (WHO), someone is infected every second with Mycobaterium tuberculosis. It is present in about one-third of the worlds population, some two billion people, although many people do not develop the disease, which is spread by coughing or spitting.

McShanes MVA85A vaccine, which was funded by the Wellcome Trust biomedical research charity, was tested in Oxford, where schoolchildren no longer routinely receive BCG. The three-year study involved 42 adults aged 18 to 55, who were divided into three groups. Results were published by Nature Medicine online.

Of two groups who had never been inoculated with BCG, one was given BCG and the other MVA85A. The third group who had previously received BCG was given MVA85A as a boost.

In volunteers given only MVA85A the trials showed it was safe and produced a high number of T cells, which fight disease. Those who had previously had BCG and were given MVA85A revealed a far greater number of these helper cells in some case up to 30 times the levels produced in the other groups. These are some of the strongest responses ever seen in a human vaccine.

More trials of the new vaccine will now take place in the developing world some are already underway in The Gambia - where TB is endemic and babies are given BCG within 24 hours of birth. In the UK is it usually administered at the age of thirteen.

McShane, a Wellcome Clinician Scientist Fellow and researcher at Oxford Universitys Centre for Clinical Vaccinology and Tropical Medicine, said: These results are phenomenally exciting. This is one of the major advances in the field of TB vaccines for over 80 years.

We will have to carry out more trials to see if this vaccine actually stops people from contracting TB but initial results show that MVA85A works perfectly well alongside BCG. It is safe and stimulates a strong immune response.

It made no difference if someone had been given BCG 38 years ago or just six months previously, the boost worked just as effectively.

It is not completely clear how long protection lasts from BCG. It was once thought to be 10 to 15 years but a recent study suggests longer. However, despite BCG vaccinations in the developing world the incidence rate of TB remains high so it clearly isnt good enough on its own. And giving extra shots does not improve the protection.

So, something like MVA85A seems to be the perfect ally to work with and enhance BCG. We are not aiming to replace it.

In the developing world we think it might be given to babies six months after birth or in adolescence, when the affect of BCG might begin to wane.

BCG induces low levels of T cells. So when you later give MVA85A the cells are reminded of the disease and build a bigger barrier to TB.

McShane, who works with Professor Adrian Hill at the Centre for Clinical Vaccinology and Tropical Medicine in Oxford, said it was also feasible that MVA85A would be safe for HIV sufferers who are susceptible to TB.

* A vaccine which contains one protein of TB, not the complete bacterium.

** Department of Health, October 2004.

The Wellcome Trust is an independent research-funding charity established in 1936 under the will of tropical medicine pioneer Sir Henry Wellcome. The Trusts mission is to promote research with the aim of improving human and animal health and it currently spends more than £400m p.a.

Oxford Universitys Centre for Clinical Vaccinology and Tropical Medicine is dedicated to using fundamental research achievements to benefit clinical practice and thereby reduce the global burden of major diseases. It is a centre of excellence for clinical trials of vaccines; for co-coordinating a global drive to reduce the worldwide toll of deaths and disabilities from major infectious diseases; and for promoting teaching and training of medical students and public health specialists in the UK and overseas.

Source: Wellcome Trust