Long term population impact of seven-valent pneumococcal conjugate vaccine with a "3+0″ schedule-How do "2+1″ and "3+1″ schedules compare?

Abstract

Introduction: Significant reductions in invasive pneumococcal disease (IPD) following 7-valent pneumococcal conjugate vaccine (7vPCV) are well documented, but population-level data comparing different schedules are sparse. We compared data from long-term stable surveillance in one Australian region (3 primary doses (3+0) schedule) with similar data from England and Wales (2+1 schedule) and the United States (3+1 schedule).

Methods: Incidence rate ratios (IRRs) for all, vaccine type, and non-vaccine type IPD were calculated by age-group, using comparable case definitions and time periods post 7vPCV introduction.

Results: At baseline, the % of IPD due to 7vPCV serotypes (VT) disease in children <5 years was 88% in Greater Sydney (GS), 83% in the United States (US), and 74% in England and Wales (E&W). IRR for VT IPD <5 years in GS was 0.05 (0.02-0.09), for ≥65 years was 0.15 (0.12-0.19) and for all ages 0.12 (0.10-0.13). In the US, IRR for VT IPD was lower in each age group, and for all ages the 95% CI of the IRR (0.06 (0.05-0.07)), did not overlap with GS or E&W (0.14 (0.11-0.18)). In contrast, the IRR for IPD due to any serotype did not differ between sites for any age group or overall.

Conclusions: Differences in direct and indirect reductions in VT IPD with a "3+0″ 7vPCV schedule versus "2+1″ or "3+1″ were small. All 3 countries moved to 13vPCV by 2011; data post 13vPCV will be important to assess IPD impact using more similar baseline incidence and comparison periods.

Keywords: Comparison; Conjugate; Pneumococcal; Schedule; Vaccination.