Impact of 10-valent pneumococcal conjugate vaccine on the epidemiology of otitis media with otorrhea among Bangladeshi children.

In 2015, Bangladesh introduced the ten-valent pneumococcal conjugate vaccine (PCV10). This study evaluates the impact of PCV10 on pneumococcal otitis media (OM), a prevalent middle ear infection among children in low-and-middle income countries, including Bangladesh. We analyzed ear swabs from OM cases with otorrhea collected at the largest pediatric hospital in Dhaka, Bangladesh from April 2014 to March 2019. The study involved identifying pathogens and conducting pneumococcal serotyping using the Quellung reaction. Four years post PCV10 introduction, the rate of detection of pneumococcus among otorrhea cases decreased from 18.4 % (164/892) in 2014-15 to 15.6 % (581/3735) in 2018-19, reflecting a 15.4 % reduction. Notably, vaccine serotypes (VTs) demonstrated a significant decline throughout the post-PCV years, with a 44.1 % reduction compared to the pre-PCV period. Specific VTs like 14, 6B and 19F exhibited significant reductions of 60.2 %, 57.5 % and 42.9 % respectively. Conversely, non-vaccine serotypes (NVTs) showed non-significant increase of 8.6 %; specifically serotype 35B showed a 70.1 % increase. Administration of two or three doses of PCV10 provided 84.4 % protection against OM cases caused by serotypes covered by PCV10. This is the first report from South Asia assessing PCV's impact on pneumococcal OM. It demonstrates a 15.4 % reduction in pneumococcal isolation over four years and over 80 % efficacy of PCV10 in preventing vaccine type pneumococcal OM cases. While some vaccine serotypes decreased significantly, the impact of PCV10 on overall pneumococcal OM cases was dampened by increasing isolation of non-vaccine serotypes.