Effect of pneumococcal conjugate vaccination on nasopharyngeal carriage in children with early onset of acute otitis media - a randomized controlled trial.

Conclusion: Although children vaccinated with heptavalent pneumococcal conjugate vaccine (PCV) had fewer episodes of acute otitis media (AOM), this trial was unable to prove a simultaneous decrease in nasopharyngeal carriage.

Objective: Carriage rates of AOM pathogens in the nasopharynx are high among children, and colonization is the first step towards infection. The possible impact of PCV on carriage is therefore of interest, particularly in children with recurrent AOM. The aims of this study were to examine the effect of heptavalent PCV on carriage of AOM pathogens in children at high risk of developing recurrent disease, and to monitor carriage of resistant pathogens in vaccinated and unvaccinated children.

Methods: A total of 109 children with an onset of AOM before 6 months of age, 89 of whom developed recurrent disease, were enrolled in a trial. Fifty-two children were vaccinated and all were closely monitored for 3 years.

Results: There was no difference statistically between vaccinated children and controls concerning the carriage of any of the major AOM pathogens. There was evidence of within-child clustering for S. pneumoniae (p = 0.002) and H. influenzae (p < 0.001), indicating that children continued to carry either species over time. Resistance rates were generally low and comparable with national levels.