Streptococcus pneumoniae carriage among healthy and sick pediatric patients before the generalized implementation of the 13-valent pneumococcal vaccine in Morocco from 2010 to 2011.

Nasopharyngeal carriage studies provide insights into the local prevalence of circulating pneumococcal serotypes. These data are critical to vaccination monitoring, as they allow for the prediction and assessment of impact. Very little data are available on the carriage of pneumococcal serotypes in Morocco. Here, we describe the prevalence of Streptococcus pneumoniae carriage and serotype distribution among 697 pediatric patients with ages ranging from 2 to 59 months who were admitted to a Moroccan hospital with severe pneumonia, as well as 195 healthy infants and young children who were recruited at a vaccination clinic. Carriage rates were 40.5% (79/195) for healthy children and 22.8% (159/697) for sick children. The most commonly observed circulating serotypes included 6A, 6B and 19F, all of which are included in the current 13-valent anti-pneumococcal conjugate vaccine that was recently introduced in Morocco. Monitoring of circulating serotypes remains necessary after vaccine introduction to assess whether serotype replacement is occurring.