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PCV7 vaccination significantly decreased invasive pneumococcal disease
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Following the introduction of the 7-valent pneumococcal conjugate vaccine in Calgary, Canada, there was a significant decrease in the number of cases of invasive pneumococcal disease among both children and adults in the area, according to new results from the Calgary-Area Streptococcus pneumoniae Research (CASPER) study.
The study involved a prospective, population-based surveillance of all cases of invasive pneumococcal disease in the Calgary Health Region between January 1998 and December 2007. The researchers collected demographic and clinical data; viable isolates were saved and serotyped.
The results demonstrated a significant decrease in the number of cases of invasive pneumococcal disease beginning in 2002, which is when routine infant vaccination with the 7-valent pneumococcal conjugate vaccine began in the area.
During the 10-year period of the study, there were a total of 1,182 cases of invasive pneumococcal disease. The researchers compared results from before and after routine vaccination began. These results demonstrated the incidence of invasive pneumococcal disease due to 7-valent pneumococcal conjugate vaccine serotypes decreased significantly by 86% among those aged 6 to 23 months, 59% among those aged 2 to 4 years, 38% among those aged 16 to 64 years, and 78% among those aged 65 to 84 years.
The researchers said the significant decrease of invasive pneumococcal disease in the Calgary area indicates “a strong direct effect and herd effect of the vaccine.”
The researchers also noted that the serotypes that now cause invasive pneumococcal disease have “changed significantly” and that the “magnitude and impact of replacement invasive pneumococcal disease caused by non-7-valent pneumococcal conjugate vaccine serotypes is not yet known.”
Kellner J. Clin Inf Dis. 2009;49:205-212.