Changing Epidemiology of Invasive Pneumococcal Disease due to Conjugate Vaccine Serotypes in Toronto, Canada After Introduction of a Routine Pediatric PCV13 Program

Abstract

Background. In Ontario a publicly funded PCV7 infant program (3 + 1 schedule), was introduced in 1/2005, PCV10 in 10/2009 and PCV13 in 11/2010 (2 + 1 schedule with catch-up to 35m). TIBDN performs population-based surveillance for invasive pneumococcal disease (IPD) in Toronto/Peel to evaluate program impact. Methods. IPD cases are reported to a central office and one isolate/case is serotyped. Demographic/ clinical data are collected by chart review and patient/physician interview. Results. From 1/1995-5/2017, 9727 IPD cases have been identified. Among 910 IPD cases since 2015, 109 (12%) were aged <15y, 376 (41%) 15-64y and 425 (41%) aged ≥65y; 57 (7%) were due to serotypes (STs) included in PCV7, 188 (24%) due to STs in PCV13 but not PCV7, 228 (30%) due to STs in PPV23 but not PCVs, and 295 (38%) due to non-vaccine STs (142 isolates not available/not yet typed). The incidence of IPD in 2016 was 4.78/100000 in children and 5.68/100000 in adults (44% and 32% reduction since 2008/9 respectively. Since 1/1/2015, there has been no IPD due to PCV7 STs in children. In adults, 57 episodes include 19 of ST4, 13 ST19F, 8 ST14, 7 ST6B, 5 ST9V, 3ST18C and 2 ST23F. The median age of patients was 64.5y (range 28-98), 37 were male; 67% had an underlying illness. PCV7 ST cases were more likely to be associated with group housing than other cases (12/45, 21%, v 47/644, 7%, P