Purpose: Updating epidemiological studies to document current incidences of pneumococcal diseases are greatly needed in the current era of new pneumococcal conjugate vaccines (PCVs). The aim of this study is to analyze the incidence and distribution of different serotypes causing pneumococcal infections among the pediatric population in southern Catalonia, Spain, throughout the 2002-2009 PCV7 eras.
Methods: A population-based surveillance study was conducted among children aged ≤ 14 years in the region of Tarragona (Catalonia, Spain) during the period 2002-2009. All cases of pneumococcal infections (invasive and non-invasive cases) were included in the study. Incidence rates (per 100,000 population-year) and prevalence of infections caused by serotypes included in different PCV formulations were calculated for the 2002-2005 and 2006-2009 periods.
Results: Globally, across the total 2002-2009 period, the incidence of pneumococcal infections was 48.2 per 100,000 children-year (22.4 and 25.8 for invasive and non-invasive infections, respectively). Between 2002-2005 and 2006-2009, the incidence rates largely decreased among children aged <2 years (from 171 to 111 per 100,000 children-year; p = 0.059), but they did not substantially vary among children aged 2-14 years. The percentages of cases caused by serotypes included in PCV7 (60.0 vs. 16.7 %; p < 0.001), PCV10 (75.0 vs. 47.4 %; p = 0.028), and PCV13 (85.0 vs. 70.5 %; p = 0.190) decreased in both periods.
Conclusion: In this study, which was conducted in a setting with intermediate PCV7 uptakes, a considerable protective direct effect of vaccination occurred among young infants, but an indirect protective effect did not emerge in the rest of the pediatric population. Despite new PCVs with higher serotype coverage, an important proportion of pneumococcal infections is still not covered by these vaccines.