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Post-PCV7 changes in colonizing pneumococcal serotypes in 16 Massachusetts communities, 2001 and 2004
Susan S Huang1, Richard Platt, Sheryl L Rifas-Shiman
1Channing Laboratory, Brigham and Women's Hospital, Boston, Massachusetts, USA.
Pediatrics
|September 6, 2005
Summary
The heptavalent conjugate pneumococcal vaccine (PCV7) led to a decrease in vaccine serotypes and an increase in non-vaccine serotypes among children. Antibiotic resistance in non-vaccine strains significantly increased, necessitating continued surveillance.
Area of Science:
- Microbiology
- Vaccinology
- Epidemiology
Background:
- The heptavalent conjugate pneumococcal vaccine (PCV7) was introduced to reduce invasive pneumococcal disease.
- Concerns exist regarding potential serotype replacement with non-vaccine strains after PCV7 introduction.
- Analyzing carriage in healthy children provides insight into these epidemiological shifts.
Purpose of the Study:
- To analyze changes in pneumococcal serotype distribution and antibiotic susceptibility in children after PCV7 introduction.
- To assess the impact of PCV7 on the carriage of vaccine-type versus non-vaccine-type Streptococcus pneumoniae.
Main Methods:
- Nasopharyngeal specimens were collected from children under 7 years old in Massachusetts between 2001 and 2004.
- Streptococcus pneumoniae isolates underwent serotyping and antibiotic susceptibility testing.
- PCV7 vaccination history was obtained from medical records.
Main Results:
- PCV7 serotypes decreased from 36% to 14% of isolates, while non-PCV7 serotypes increased from 34% to 55%.
- Overall pneumococcal carriage rates remained stable, but carriage of non-PCV7 serotypes significantly increased.
- Penicillin nonsusceptibility rose substantially in non-PCV7 serotypes, tripling in proportion.
Conclusions:
- Pneumococcal colonization patterns have shifted post-PCV7 introduction, with increased prevalence of non-vaccine serotypes.
- A significant rise in penicillin nonsusceptibility among non-vaccine pneumococcal isolates was observed.
- Vigilance is crucial to monitor for changes in invasive pneumococcal disease epidemiology due to these shifts.