The Changing Epidemiology of Invasive Pneumococcal Disease Among the Indigenous and Non-indigenous Population of Northwestern Ontario, Canada, from 2006 Through 2015 and Emergence of Non-vaccine Serotypes

Abstract

BackgroundRates of invasive pneumococcal disease (IPD) among indigenous populations remain substantially higher than their non-indigenous counterparts. The goal of this study was to analyze the epidemiology and demographic features of IPD in northwestern Ontario (NWO) among the indigenous and non-indigenous population in the context of recent changes in the provincial pneumococcal vaccination programs.MethodsTwo databases were used to identify cases of IPD in NWO: Thunder Bay Regional Health Sciences Centre and the Thunder Bay District Health Unit. Adult patients with a diagnosis of IPD at the TBRHSC from January 1, 2006 to December 31, 2015 had their medical charts retrospectively reviewed; TBDHU data contained only serotype, age, and gender data.ResultsTable 1.Number of IPD cases and case fatality rate by indigenous status at the TBRHSC, 2006–2015# of cases# of deathsyearindigenousnon-indigenoustotalindigenousnon-indigenoustotal2006371000020070880112008511160112009820282022010517220222011622281122012381101120131012221342014101121000201531316022total531291824111553 of 182 (29.0%) of patients were indigenous. 35 of 53 (66.0%) of indigenous patients were immunocompromised, whereas 38 of 129 (29.5%) of non-indigenous patients were immunocompromised and the difference was statistically significant (P < 0.001, by chi square test). 35 of 73 (48.0%) of immunocompromised patients were indigenous.Table 2.Serotype distribution of Streptococcus pneumoniae causing IPD in northwestern Ontario, Canada, 2006–2015 (includes both TBRHSC + TBDHU data).yearPCV7PCV13PCV23non-vaccine serotypesunknown serotypestotal200600002626200710211216200822541427200931293164320100784123120112101249372012021184252013032128342014129382320151076923total10388435118285The proportion of non-vaccine serotypes has increased, on average, by 16% per year (P = 0.024, 95% CI: 1.02, 1.32).ConclusionHigh rates of IPD were found to occur among immunocompromised indigenous adults in NWO. Our findings identify a vulnerable cohort of the population that would benefit from pneumococcal vaccination coverage. The proportion of non-vaccine serotypes causing IPD has increased during the 10-year observation period.Disclosures M. Ulanova, Pfizer: Grant Investigator, Grant recipient