Effect of 7-valent pneumococcal conjugate vaccine on nasopharyngeal carriage with Haemophilus influenzae and Moraxella catarrhalis in a randomized controlled trial

Seven-valent CRM197-conjugated pneumococcal conjugate vaccine (PCV7CRM197) reduces both vaccine serotype nasopharyngeal colonization and vaccine serotype acute otitis media by 50-60%. However, overall pneumococcal carriage and impact on otitis media are partly offset by concomitant increase of nonvaccine serotypes. We investigated in a randomized controlled trial the impact of 2-doses and 2 + 1-doses of PCV7CRM197 on carriage of Streptococcus pneumoniae and of other nasopharyngeal commensals and well-known otitis media pathogens, Haemophilus influenzae and Moraxella catarrhalis, in children. Nasopharyngeal swabs were collected at the age of 6 weeks and at 6, 12, 18 and 24 months. We observed high carriage rates up to 68% for S. pneumoniae, 71% for H. influenzae and 68% for M. catarrhalis at the age of 18 months. Reduced dose CRM197 schedules induced a slight reduction in overall pneumococcal carriage but no increases in the presence of H. influenzae and M. catarrhalis.