Towards the 13-valent pneumococcal conjugate universal vaccination. Effectiveness in the transition era between PCV7 and PCV13 in Italy, 2010-2013

Pneumococcal disease epidemiology has changed after introduction of pneumococcal conjugate vaccines. Seven-valent vaccine (PCV7) has been effective in reducing invasive pneumococcal disease (IPD). In europe, PCV13 effective-ness was estimated at 78% (95% CI:-18–96%) for 2-priming doses. In Italy, PcV7 was introduced in 2006 in the childhood immunization schedule and replaced with PcV13 in 2010. In apulia, vaccination coverage has reached 95.1% (birth-cohort 2010). We estimated PCV program effectiveness and its impact on S.pneumoniae diseases. PCV Effectiveness: We used the screening method. We calculated the Proportion of Population Vaccinated from immunization registries and detected cases through a laboratory-confirmed surveillance among hospitalized children ≤60 months. a confirmed IPD case was a child with PCR positive for S.pneumoniae. Differences among children were assessed with the chi-square or the Fisher exact test (P value < 0.05). PCV Impact: We constructed time series using outcome-specific Poisson regression models: hospitalization rate in pre-PcV era and hospitalization Risk Ratios (RRs) with 95% cIs for both PcV7 and PcV7/PcV13 shifting era. We calculated hospitalization RR with 95% Cls comparing pre-PcV years with vaccination period. The PCV effectiveness was 84.3% (95% CI: 84.0–84.6%). In May 2010-January 2013, we enrolled 159 suspected IPD of whom 4 were confirmed. Two (fully vaccinated) were caused by serotype 9V,1(not vaccinated) by serotype 3, 1 (vaccinated with 2 PcV13 doses) by 15B/c. The most important reduction was for pneumococcal pneumonia (RR: 0.43, 95% CI: 0.21–0.90). The PcV program show promising results in terms of both PCV13 effectiveness and its impact in reducing IPD in children < 5 years.