A new vaccine introduced in July will further reduce the number of cases of invasive pneumococcal disease. The disease can cause pneumonia, a blood infection and meningitis.
Since the introduction of a vaccine in 2008 covering the seven most common types of the disease, the number of cases has dropped significantly.
In 2007, there were 156 cases of invasive pneumococcal disease in children under five and in 2012, that had dropped to 58.
Helen Petousis-Harris, director of research at the Immunisation Advisory Centre, says a number of cases are caused by strains not covered by the current vaccine. She hopes the new vaccine that protects against 13 strains will lead to further reductions.
"We would expect to see probably a more modest reduction now in disease but there's certainly, especially in some of the older age groups, disease caused by those other types."
Ms Petousis-Harris says while pneumococcal disease will not be eliminated completely, the vaccine helps to put a big dent in the number of cases.