The vaccine is made of dead bacteria isolated from samples of African soil and is believed to produce an immune reaction that protects asthma sufferers from the particles in the air that can trigger an attack.
Stephen Holgate, professor of immunopharmacology at the University of Southampton, emphasised that the early results come from a small-scale study of just 24 asthmatic students, half of whom were injected with the vaccine with the other half receiving a placebo.
He told the British Association's meeting in Sheffield yesterday that the study demonstrated that those injected with the vaccine experienced a 30 per cent reduction "in the ability of the human asthmatic airway to become inflamed and subsequently narrow in response to inhaled dust- mite antigens.
"Two-thirds of the patients did very well, and one-third of them did not change very much at all. We haven't done a formal clinical trial yet, so this was a very controlled experiment," Professor Holgate said. The next stage will be to begin a large-scale trial in the hope of being able to produce a vaccine that could help the one in 10 children who suffer from dust-mite allergy.
A vaccine made of a dead soil bacteria fits in with a theory of asthma that suggests it is an allergic response to a more hygienic environment. The theory says that children whose immune systems are not challenged by conventional microbes will become allergic to less conventional allergens - such as dust mites.
Doctors know immune reactions are linked with a child's likelihood of developing asthma. "Children who have poor reactions of BCG vaccine early in infancy are those that tended to develop asthma and allergic disease," said Professor Holgate. "Whereas those that had a good reaction when they had their injection in the first two or three years of life were relatively protected against allergic disease."
In the past 20 years asthma and eczema incidence has increased four-fold in the UK, and asthma is 23 times more common in Britain than in Albania. Professor Holgate said three separate studies in Europe had recently shown that children raised on farms containing livestock have about 60 per cent less allergy than those not living with animals. "It is suggested that some children are exposed to high levels of bacteria or their products when coming into early contact with animals, and that this confers protection (or immunity) against allergy," he said. He said research in Africa had suggested that people who had pigs living in their homes enjoyed extra protection.
A spokesman for the National Asthma Campaign said: "The research is very interesting. We have worked closely with Professor Holgate and respect his work, and look forward to further investigation and future studies."