BACKGROUND: Since pediatric national immunization programs (NIPs) switched from the 7-valent (PCV7) to the 13-valent pneumococcal conjugate vaccine (PCV13), invasive pneumococcal disease (IPD) attributable to the additional six serotypes in PCV13 has declined. The objective of this study was to investigate the annual population-level impact of PCV13 NIPs on IPD incidence due to PCV13-unique serotypes (1, 3, 5, 6A, 7F, 19A) among children and adults.
METHODS: We reviewed surveillance data from countries that introduced PCV7 followed by PCV13 in their NIP and reported annual serotype- and age-specific IPD incidence (Australia, Canada, Israel, England & Wales, and the United States). For each age group (<2, 2-<5, and ≥65 years), we calculated the annual relative change in IPD incidence and incidence rate ratio (IRR) compared to the year prior to PCV13 program initiation.
RESULTS: Decreases in PCV13-unique serotype IPD incidence in each age group were generally consistent in the five countries following the introduction of PCV13 in the pediatric NIP (Figure 1). Over an 80% average reduction in IPD caused by PCV13-unique serotypes (IRR=0.2) among <2 and 2-<5 year olds and approximately a 60% average reduction among ≥65 year olds (IRR=0.4) was observed after four years of pediatric PCV13 use (Figure 2). PCV13-unique serotype IPD incidence decreased more rapidly among children than adults in the first years of PCV13 use. From year 5 onwards, IPD incidence plateaued among all age groups.
CONCLUSIONS: Surveillance data from these five countries suggest that pediatric PCV13 use provides a high degree of direct and indirect protection against PCV13-unique serotypes.
