The Authors present the results of a multidisciplinary study carried out on a sample of 103 children comprised in a programme of vaccination against Streptococcus pneumoniae infections, in order to avoid the worsening of their asthma. In the nasopharyngeal exudate of 39 children, we detected the presence of S. pneumoniae strains of serotypes 6, 8, 14, and 19 and their absence after vaccination with PNEUMO 23. This was followed by a significant decrease in the incidence of pneumococcal infections and also by the reduction in the frequency of crises and severity of the disease.