Tests of the first vaccine against tuberculosis in more than 80 years have shown that it is safe and probably effective against the killer disease, which is spreading again as it becomes resistant to conventional drugs.

Tests of the first vaccine against tuberculosis in more than 80 years have shown that it is safe and probably effective against the killer disease, which is spreading again as it becomes resistant to conventional drugs.

The "phase one" clinical trials of the new vaccine are "phenomenally exciting", scientists said yesterday. The trials suggest that it could boost immunity in people who have already been inoculated with the existing TB vaccine, called BCG, which was first introduced in Britain in 1921.

Two further sets of clinical trials involving many thousands of people will be needed, however, before the vaccine is proven to be safe and effective. These could take five to 10 years and are likely to be conducted in the developing world where TB is still a major killer.

The vaccine, called MVA85A, is not designed to replace the BCG vaccine but to complement it by stimulating the body's immune system to launch an even more effective attack against the invading TB microbe - which has affected humanity for thousands of years and still kills about 2 million people annually worldwide. In the 20th century, vaccination and modern drugs had almost eradicated TB from the developed world but in recent years the disease has made a comeback because of the rise of drug-resistant strains which attack the most vulnerable members of society, such as the poor and homeless.

In England, the number of cases has risen by a quarter over the past decade, claiming about 350 lives a year. Earlier this month, Sir Liam Donaldson, the Chief Medical Officer, announced new measures to combat the infection. The MVA85A vaccine contains a protein taken from a TB microbe that stimulates the body's immune system to fight the infection. It was tested for safety in a three-year trial in Oxford involving three groups of 42 adults aged 18 to 55.

Of two groups whose members had never been inoculated with BCG, one was given the old vaccine and the other MVA85A. The third group, whose members had previously received BCG, was given an MVA85A booster.

The trials showed that receiving the new vaccine on its own was safe, and produced a high number of infection-fighting T-cells in the blood - one of the first lines of defence against invading diseases.

But those given MVA85A on top of BCG generated a far larger number of these cells - in some cases up to 30 times the levels in the other groups.

These were some of the strongest immune system responses ever seen in a human vaccine, the researchers say in the journal Nature Medicine.

Helen McShane from Oxford University whose team developed the vaccine with funding from the Wellcome Trust research charity, 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 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.

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

It is not clear how long BCG protection lasts. The high worldwide incidence of TB, despite BCG, suggested that the vaccine was not working sufficiently well on its own.

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