A 13-year Survey of Pneumococcal Nasopharyngeal Carriage in Children with Acute Otitis Media Following PCV7 and PCV13 Implementation

Background: This nasopharyngeal (NP) carriage surveillance study was requested by the European Agency for the Evaluation of Medicinal Products as a post-licensing commitment to determine whether the use of the pneumococcal conjugate vaccines (PCVs) including 7 then 13 valents (introduced in 2001 and 2010, respectively) caused a shift in the distribution of Streptococcus pneumoniae serotypes in children with acute otitis media and modified the resistance of this bacterial species to antibiotics.

Methods: Between 2001 and 2014, 121 pediatricians obtained nasopharyngeal swabs from children with acute otitis media aged 6-24 months. The swabs were analyzed by the French National Reference Centre for Pneumococci. Demographics, medical history and physical examination findings were recorded.

Results: Over the 13 years, among the 7991 enrolled patients, the proportion of PCV-vaccinated children (≥1 dose) increased (54.3-99.7%, p<0.001). Overall, pneumococcal carriage was reduced from 71.2% to 56.2% from 2001 to 2014 (p<0.001) and carriage of PCV7 serotypes (STs) from 44.5% to 1.2% (p<0.001). The carriage of 6 additional STs plus 6C increased from 17.2% to 24.3% from 2001 to 2010 (p<0.001) and decreased after PCV13 implementation (21.4-3.5%, p<0.001). The proportion of ST 19A carriage increased from 8.6% to 15.8% from 2001 to 2010 (p<0.001) and decreased to 1.2% in 2014. After PCV13 implementation, the most frequently carried non-PCV13 STs were ST 15B/C, 11A, 15A, and 35B. Penicillin non-susceptible pneumococcal strains decreased from 67.1% in 2001 to 33.1% in 2014 (p<0.001).

Conclusions: By the number of patients enrolled and the duration, this study is the largest performed to date. It allows to demonstrate a strong impact of PCVs and to describe the complex dynamics of pneumococcal carriage during AOM. As pneumococcal carriage decreased during AOM, a reduction in the incidence of pneumococcal AOM could be expected.