Prevalence of pneumococcal nasopharyngeal colonization and serotypes circulating in Cameroonian children after the 13-valent pneumococcal conjugate vaccine introduction.

•Overall pneumococcal carriage prevalence was 61.8% and PCV13-type pneumococci prevalence was 18.0% , four years following PCV13 implementation Ø Eleven of the thirteen vaccine serotypes continue to circulate in the population in 2015, four years after vaccine introduction.•Either the vaccination programme with the 3+0-dose schedule is not eliciting sufficient protection against vaccine-serotypes transmission or,•There are programmatic challenges with the programme.