Changing epidemiology of invasive pneumococcal disease following increased coverage with the heptavalent conjugate vaccine in Navarre, Spain

The present study evaluated changes in the incidence of invasive pneumococcal disease (IPD) and the pattern of serotypes isolated in Navarre, Spain, after the introduction and increased coverage of the heptavalent pneumococcal conjugate vaccine (PCV7). All cases with isolation of pneumococcus from normally sterile bodily fluids were included. The incidence of IPD in children and adults was compared for the periods 2001–2002 and 2006–2007. By the end of 2002, only 11% of children aged <5 years had received any dose of PCV7, whereas, beginning in 2007, the proportion exceeded 50%. Among the cases of IPD aged <5 years, the percentage of those vaccinated increased from 7% during 2001–2002 to 53% during 2006–2007 (p <0.001). The incidence of IPD from PCV7-serotypes decreased by 85% in children <5 years (p <0.001), by 45% in the population aged 5–64 years (p 0.10) and by 68% in those ≥65 years (p 0.004). By contrast, the incidence of IPD from non-PCV7 serotypes increased by 40% overall (p 0.006). The incidence of IPD from all serotypes did not change significantly in children <5 years (from 83 to 72 per 100 000) or in the total population (from 15.8 to 16.3 per 100 000). The percentage of cases as a result of serotypes 7 and 19A increased significantly in both children and adults. No significant changes were seen in the clinical forms of IPD. The pattern of serotypes causing IPD has changed, in both children and adults, following the increased coverage of PCV7, although the incidence has been reduced only slightly.