A discovery by Irish scientists could lead to the development of an improved vaccine against whooping cough.

Whooping cough (pertussis) is a highly contagious respiratory disease caused by the bacteria Bordetella pertussis. It is known for uncontrollable, violent coughing which can make it difficult to breathe.

After a bout of coughing, someone with pertussis often needs to take in a deep breath which results in a 'whooping' sound. Pertussis most commonly affects infants and young children and can be fatal, especially in babies less than one year of age.

According to scientists at Trinity College Dublin (TCD), their discovery could reduce the incidence of the disease, which is on the rise in developed countries. Just last year in Ireland, the HSE issued new guidelines to protect very young babies as a result of an ongoing whooping cough outbreak.

By the end of 2012, the number of cases of the disease here had doubled and two infant deaths had been recorded. As a result, the HSE recommended that pregnant women who had not received a whooping cough vaccine in the previous 10 years, should be offered a booster vaccine in late pregnancy to help protect their babies.

The current vaccine against whooping cough was introduced to the routine vaccination schedule for children in most developed countries, including Ireland, over 10 years ago. Before this, children were vaccinated with a vaccine made from whole bacteria, known as ‘whole cell pertussis vaccine'. While this was successful at preventing whooping cough, side-effects were often reported.

As a result, a new vaccine was developed. Known as ‘acellular pertussis vaccine', this is made up of components of the bacteria. These are then combined with an adjuvant - a immunological agent added to a drug to increase or aid its effect.

While this vaccine does work and is associated with fewer side-effects, immunity wears off relatively quickly, necessitating the need for booster shots.

However, the scientists at TCD have discovered important differences between the types of immune responses brought about by the two different vaccines. These differences are related to white blood cells in the body, called T cells.

The team has found that the current vaccine may be improved if another adjuvant is used. Currently, the vaccine is combined with an aluminium salt - alum. The team found that if alum was replaced with an adjuvant based on bacterial DNA, the efficacy of the current vaccine could be improved. This could have the potential of protecting more children with lower doses of the vaccine.

"Although it will not be an easy task to implement, our findings should pave the way for an improved vaccine against whooping cough in children," commented lead scientist, Prof Kingston Mills.

Details of these findings are published in the journal, PloS Pathogens.

For more information on the whooping cough vaccine and vaccines in general, see our unique Child Immunisation Tracker here