[Nasopharyngeal carriage of children 6 to 60 months during the implementation of the 13-valent pneumococcal conjugate vaccine].

BACKGROUND: Since 2001 in France, a nasopharyngeal carriage study was set up for children six to 24 months old. Any data are available for older children (25 to 60 months). The aim of this study is to compare the nasopharyngeal carriage in children with acute otitis media (AOM) or healthy between both age groups (6/24 months versus 25/60 months). Moreover, during the study period, the 13-valent pneumococcal conjugate vaccine (PCV13) has replaced PCV7 in June 2010.

METHODS: From October 2010 to June 2011, 58 pediatricians obtained nasopharyngeal swabs from children 6-60 months with acute otitis media (AOM) or healthy controls, to analyse the carriage of pneumococcus, Haemophilus influenzae, Moraxella catarrhalis, group A streptococcus and Staphylococcus aureus.

RESULTS: Of the 1557 enrolled children, 1258 were 6 to 24 months old (315 healthy and 943 AOM) and 299 were 25 to 60 months (102 healthy and 197 AOM). More then 85% were PCV7 vaccinated and the children of 25/60 months were rarely PCV13 vaccinated (14.1%) compared to younger children (69.9%, P<0.001). For children 6/24 months, the Streptococcus pneumoniae carriage was higher in AOM group (57.3%) versus healthy (28.9%). By contrast for older children, the difference (58.4% versus 50%) was not significant. In the healthy group, older children carried more often S. pneumoniae than younger children (50% versus 28.9%, P<0.0001). This trend was also observed for H. influenzae carriage (49% versus 18.7%, P<0.0001). Multivariate analysis in the healthy group showed that siblings and day care center (or school) increased the carriage of S. pneumoniae and H. influenzae.

CONCLUSION: These data from nasopharyngeal carriage in children 6 to 60 months old showed that pneumococcus and H. influenzae carriage is high for patients under 2 years, especially in the healthy group. Moreover, these data from the transition PCV7/PCV13, will serve as baseline in France to evaluate the impact of PCV13.