Emerging of non-vaccine Streptococcus pneumoniae serotypes colonizing the nasopharynx of children under the age of five years in the 13-vallent pneumococcal conjugate vaccine era in Moshi district, Tanzania. A short communication.

In this study, we describe S. pneumoniae serotype distribution before and after PCV13 rollout in Tanzania. We serotyped S. pneumoniae isolates from two cross-sectional studies, before and after vaccine rollout. The isolates were from children under 5 years old, and in the PCV13 era, only those who had received all doses of PCV13 were eligible. Total of 539 participants with serotyped S. pneumoniae were included. In the pre-vaccine era, 61 (55 %) of S. pneumoniae serotypes were vaccine types, compared to 89 (23.3 %) in the PCV13 era. The most common serotypes in the pre-vaccine period were 19F (n = 23, 20.7 %) and 6B (n = 11, 9.9 %). In the vaccine era, serotypes 15B/C (n = 40, 10.5 %), and 3 (n = 29, 7.6 %) were most prevalent. We observed the emergence of 14 non-vaccine serotypes not detected in the pre-vaccine era. Further surveillance is needed to assess shifts in carriage and their implications for the fight against invasive pneumococcal disease.