Invasive pneumococcal disease in Catalonian elderly people, 2002-2009: Serotype coverage for different anti-pneumococcal vaccine formulations at the beginning of the new conjugate vaccines era

Population-based surveillance study conducted among persons 65 years or older from the region of Tarragona (Southern Catalonia, Spain) during 2002-2009. All cases with isolation of pneumococcus from normally sterile bodily fluids were included. Incidence rates of invasive pneumococcal disease (IPD) and prevalence of infections caused by serotypes included in different pneumococcal conjugate vaccines (PCVs) and the 23-valent pneumococcal polysaccharide vaccine (PPV-23) were calculated. Overall, 176 IPD cases were observed, which means an incidence of 48 episodes per 100,000 person-year throughout the study period. The most dominant serotypes were 7F (10.1%), 14 (9.4%), 19A (9.4%), 3 (8.6%), 6A (7.9%) and 1 (7.2%). IPD cases due to PCV-7 types (from 37.2% to 14.6%; p = 0.003) and PCV-10 types (from 60.5% to 32.3%; p = 0.002) considerably decreased between 2002-2005 and 2006-2009 periods. Percentage of cases due to PCV-13 types (76.7% vs 62.5%; p = 0.099) and PPV-23 types (81.4% vs 68.8%; p = 0.122) did not significantly change between both periods. As main conclusion, in our setting, the PCV-13 has almost similar serotype coverage to the PPV-23 in preventing IPD among the elderly population, which suggests a possible future use of the conjugate vaccine in all age groups.