This website uses cookies. By using our website you consent to all cookies in accordance with our Privacy Policy. Read more - OK, thanks

Back to Suggested Publications

Wednesday 26 August 2015
From PCV7 to PCV13 in Norway

Decreased Carriage and Genetic Shifts in the Streptococcus pneumoniae Population After Changing the 7-Valent to the 13-Valent Pneumococcal Vaccine in Norway, the article recently published on PIDJ.

SUMMARY

Streptococcus pneumoniae commonly colonizes the human nasopharyngeal epithelium. Children carry pneumococci more often and for longer episodes than adults, and are considered the main reservoir. Pneumococcal carriage can lead to disease. Pneumococcal conjugate vaccines  (PCV) have been widely implemented in childhood immunization programs and have been  shown to effectively prevent both IPD and asymptomatic carriage of vaccine serotypes (VT). To understand and predict post-vaccination changes in IPD, the dynamics in serotype and genotype diversity of carried strains should be studied. The authors assessed vaccine-induced changes in carriage prevalence and in serotype and genetic diversity of pneumococci carried by children. Results from a cross-sectional carriage study conducted almost two years after switching from PCV7 to PCV13 were compared to similar samples taken before mass vaccination with PCV7 and almost two years after PCV7 introduction. Nasopharyngeal swabs were obtained. Serotyping, multilocus sequence typing and antimicrobial susceptibility testing were performed on all isolates.
Carriage of PCV13 serotypes has decreased without a coinciding increase in non-PCV13 serotypes. The serotype and genetic shifts among non-PCV13 serotypes suggest that a new equilibrium has not yet been reached. As the few non-PCV13 serotypes that increased have generally a lower invasive capacity than vaccine serotypes, direct and indirect protection of PCV13 on IPD can be expected to continue.

AUTHORS: Anneke Steens, Dominique A. Caugant, Ingeborg S. Aaberge, and Didrik F. Vestrheim