The British Lung Foundation says it is closer to finding a vaccine for breathing problems suffered by babies in winter.

Experts believe the results of a three year study give them a better understanding of what causes the viral infections common amongst children in the first year of their lives.

They have identified how infants' immune systems react to these infections - called bronchiolitis - which are the greatest cause of hospital admissions among babies in the developed world.

The condition often starts in infants as a common cold but then develops into breathlessness.

This is real progress towards finding a vaccine that could eventually protect infants

Dr Imran Hussain

The research team headed by Dr Imran Hussain at Southampton General Hospital studied the immune responses of asthmatic and non-asthmatic children by observing white blood cells collected from their tonsils.

They were able to gain a clearer understanding of how the blood cells react to the most common form of bronchiolitis - respiratory syncytial virus (RSV).

The project identified RSV infections as causing harm to the immune system that would normally protect children from allergic reaction.

Vital clues

It is hoped this breakthrough could now provide vital clues in the search for a vaccine for RSV.

Dr Hussain said: "This is real progress towards finding a vaccine that could eventually protect infants, especially those most at risk, such as premature babies, from developing this all too common type of respiratory problem.

"Although this condition is rarely life-threatening and can often seem little more than a bad cold, it is obviously uncomfortable and distressing for the child and extremely worrying for the parents."

Some babies will recover from the condition without treatment, but those under six weeks old or with congenital heart defects should be given medical attention immediately.

The British Lung Foundation has also published a factsheet on bronchiolitis which gives parents tips on how to recognise the condition and ease the symptoms.

Factsheets are available by sending a stamped addressed envelope to the foundation at 78 Hatton Garden, London EC1N 8LD.