1475 - Impact of a Routine Infant PCV Program on the Serotype Distribution of Episodes of Invasive Pneumococcal Disease (IPD) and Non-bacteremic Pneumococcal Pneumonia in Adults

Background: Herd immunity from pediatric pneumococcal conjugate vaccine (PCV) programs has resulted in substantial reductions in IPD due to PCV serotypes (ST). We assessed whether similar changes in ST distribution occur in non-bacteremic pneumococcal pneumonia (NBPP).

Methods: The Toronto Invasive Bacterial Diseases Network performs population-based surveillance for IPD and hospitalized, culture-confirmed NBPP in Toronto/Peel Region, Canada (Pop 4.5M). Patient data are collected by interview/chart review; illness associated with respiratory isolates is categorized using Musher criteria.

Results: Since 2002, 6627 episodes of IPD, and 7323 non-bacteremic episodes with a respiratory isolate of S. pneumoniae (2180 meeting modified Musher criteria for NBPP) have occurred in adults. Distributions of vaccine-type serotypes in IPD and NBPP pre-PCV7 (2002-2004), post-PCV7 (2006-2009) and late post-PCV13 (2014-2019) are shown in the Figure. There were no significant changes in distribution of vaccine serotype groups from 2014-2019 in IPD or NBPP. From 2014-2019, serotypes included in PCV13 and PCV20 were associated with 33% and 59% of IPD cases, and 29% and 49% of NBPP cases in adults..Figure. distribution of serotype groups included in different pneumococcal vaccines in cases of IPD and non-bacteremic pneumonia


Conclusion: Eight years post routine infant PCV13 implementation, PCV13 type IPD and NBPP persists in adults. The distribution of vaccine-type strains is similar in IPD and NBPP; although non-vaccine-type strains are more common in NBPP.