New TB vaccine shown to be safe

One third of the world's population is though to carry the TB bacterium

The first TB vaccine to be developed in more than 80 years has passed safety trials in the UK.

Oxford University researchers say the vaccine could boost the power of the existing BCG vaccine.

The study, in Nature Medicine, suggests the new vaccine could be of particular use in the developing world, where cases of tuberculosis are rising.

The World Health Organization estimates one person is infected every second. It kills two million people annually.

We're never going to get rid of TB unless we have a decent vaccine Paul Sommerfeld, TB Alert

It is believed to be present in about one-third of the world's population, around two billion people, although many people do not develop the disease.

In England, the number of cases of TB has risen by 25% over the last decade.

The BCG vaccine is thought to offer protection for around 15 years.

But it is not effective for everyone. In the UK, only around two thirds of those who receive the vaccination are believed to be protected. Some trials have suggested protection could be as low as 30%.

'Helper' cells

The new MVA85A vaccine was tested in Oxford, where schoolchildren no longer routinely receive BCG.

The three-year study, which was funded by the Wellcome Trust research charity, involved 42 adults aged 18 to 55, who were divided into three groups.

Two groups had never been vaccinated with BCG. One of these was given BCG and the other MVA85A.

People in the third group, who had previously received BCG, were given MVA85A as a boost.

In those who were only given MVA85A, the trials showed it was safe and produced a high number of T 'helper' cells, which fight disease.

Those who had previously had BCG and were given MVA85A revealed a far greater number of T cells, in some case up to 30 times the levels produced in the other groups.

The researchers now plan to test the research in the developing world. A trial is already underway in The Gambia - where TB is endemic and babies are given BCG within 24 hours of birth.

In the UK, BCG is usually administered at the age of thirteen.

An 'ally' vaccine

Dr Helen McShane, a Wellcome Clinician Scientist Fellow and researcher at Oxford University's Centre for Clinical Vaccinology and Tropical Medicine, who led the study, said: "These results are phenomenally exciting.

"This is one of the major advances in the field of TB vaccines for over 80 years."

She added: "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."

Dr McShane said MVA85A appeared to work as an "ally" with BCG, rather than as a replacement.

"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."

Paul Sommerfeld, chair of TB Alert, said: "It's very encouraging because, in the long term, we're never going to get rid of TB unless we have a decent vaccine.

"At the moment we have a vaccine which is better than nothing but a very long way off being what we need."

But he added: "This is a very early step. A useable vaccine is still a long way away, perhaps a decade off."