Impact of Widespread Introduction of Pneumococcal Conjugate Vaccines on Pneumococcal and Nonpneumococcal Otitis Media

Background. Pneumococcal conjugated vaccines (PCVs) impact on complex otitis media (OM; including recurrent, nonresponsive, and chronic OM with effusion) was greater than that on simple, acute OM in previous studies. Since complex OM is often a polymicrobial disease, we speculated that reduction of complex OM by PCVs would be associated with reduction of non-pneumococcal OM. Methods. In a prospective, population-based, active surveillance, all OM episodes submitted for middle ear fluid culture in children <3 years from 2004 through 2015 were included. Three sub-periods were established: pre-PCV, PCV7, and PCV13. Incidence rate ratios (IRRs) comparing the 3 periods were calculated for pneumococcal, nontypable Haemophilus influenzae (NTHi), Moraxella catarrhalis, Streptococcus pyogenes, and culture-negative OM. Results. Overall, 7475 episodes were included. Of all-NTHi cases in the pre-PCV period, 34% were mixed with Streptococcus pneumoniae. IRRs (95% confidence interval) comparing the pre-PCV to the PCV13 period were 0.02 (0.01-0.04), 0.12 (0.08-0.20), and 0.18 (0.15-0.21) for PCV7+6A serotypes, 5 additional PCV13 serotypes, and all-pneumococcal OM, respectively; non-PCV13 serotype episodes were not significantly reduced. IRRs for single NTHi, mixed NTHi + S. pneumoniae, and all-NTHi OM were 0.30 (0.25-0.35), 0.18 (0.13-0.24), and 0.25 (0.22-0.29), respectively. Moraxella catarrhalis, S. pyogenes, and culture-negative episodes were also significantly reduced. Conclusions. Both pneumococcal and non-pneumococcal OM episodes, enriched with complex cases, declined substantially in children <3 years following sequential PCV7/PCV13 introduction. The reduction in non-pneumococcal episodes may be attributed to early OM episodes prevention, resulting in a lower rate of complex, often non-pneumococcal OM.