Abstract
Streptococcus pneumonie is the most important agent, which cause invasive pneumococcal diseases among children uder age 5. In the USA, Prevnar, a 7-valent conjugated pneumococcal vaccine, demonstrated its substantial direct and indirect effects on the incidence of invasive pneumococcal diseases (IPD). As a matter of fact, its introduction led to a dramatic decrease in invasive pneumococcal diseases both in children and, indirectly, also in the senior age cohorts.
In addition, lower pneumococci colonisation of the mucosa, constituting this indirect effect, leads to a lower incidence of acute otitis up to 2 years of age. The use of Prevenar also decreases the incidence in the population of Streptococcus pneumoniae strains that are resistant to penicillin or erythromycin.