Background: The 7-valent pneumococcal conjugate (PCV7) vaccine's impact on invasive pneumococcal disease (IPD) is well described, but few reports exist on the additional impact of the 13-valent vaccine (PCV13).
Methods: We calculated the IPD incidence across all ages in a surveillance project following implementation of PCV7 (in September 2006) and PCV13 (in April 2010) in children aged <2 years (11 hospitals; 4935 cases).
Results: The overall incidence decreased from 10 cases/100 000 persons per year in 1996-1997 to 8 cases/100 000 persons per year in 2007-2008 and 7 cases/100 000 in 2012-2013. Declines were greater in children aged <2 years (from 37 cases/100 000 in 1996-1997 to 29 and 14 cases/100 000 in 2007-2008 and 2012-2013, respectively). The incidence of IPD due to PCV7 serotypes decreased in all ages after PCV7 introduction (P < .001), whereas the incidence of IPD due to the additional 6 serotypes in PCV13 and to nonvaccine types (NVTs) increased in children aged ≥2 years (P < .001 for both comparisons). The incidence of IPD due to the 6 additional serotypes in PCV13 declined significantly after PCV13 introduction in all ages (P ≤ .01), and the incidence of IPD due to NVTs declined significantly in children aged ≥2 years (P = .003). In 2011-2013, the overall incidences of IPD due to PCV7 serotypes, the 6 additional serotypes in PCV13, and NVTs were 0.3, 2.8, and 4.4 cases/100 000; the incidences among children aged <2 years were 0.9, 2.4, and 10.8 cases/100 000, respectively.
Conclusions: The annual incidence of IPD due to vaccine serotypes (1-3 cases/100 000) among children aged <2 years and nontarget groups demonstrates the success of PCV7 and PCV13. A substantially higher incidence of IPD due to NVTs indicates the importance of ongoing surveillance and extension of vaccine polyvalency.
Keywords: 13-valent pneumococcal conjugate vaccine; 7-valent pneumococcal conjugate vaccine; Streptococcus pneumonia; epidemiology; invasive pneumococcal disease; pneumococcal conjugate vaccines.
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