Long-term trends in invasive pneumococcal disease in Manitoba, Canada

Abstract

Invasive pneumococcal disease (IPD) remains a significant public health problem in Manitoba, Canada although publically-funded pneumococcal conjugate (PCV7 and PCV13) and polysaccharide (PPV23) vaccination programs exist. We analyzed routine surveillance and administrative health data to examine trends in IPD rates as these vaccines were introduced. Data on all individuals with a laboratory-confirmed diagnosis of IPD between 2001 and 2014 were obtained from the provincial Communicable Diseases Surveillance database and linked with Manitoba's provincial immunization registry and physician and hospital databases. We calculated IPD incidence rates overall, by serotype and for different population subgroups defined by socio-demographic and clinical (e.g., chronic diseases, immune status) characteristics. Annual IPD incidence (95%CI) was 8.6 (8.2–9.1)/100,000 people during the study period (n = 1092), and rates were higher in recent years and in regions with predominately indigenous populations. Reduction in the incidence of serotypes included in PCV7 have been offset by rising rates of PCV13-only serotypes in children, and more recently by rising rates of PPV-only serotypes and non-vaccine serotypes among young children and older adults (≥ 65 years). Rates were 3 times higher in those with a chronic disease and highest (> 175-fold) among alcoholics, organ-transplant, and chronic kidney failure patients. The case fatality rate was 12.0% within 30 d of diagnosis. Despite the introduction of several vaccination programs, overall rates of IPD have not declined in Manitoba in the last decade, due to increase in incidence of non-PCV7 serotypes. A disproportionately high burden of disease impacts indigenous communities and people with chronic disease.

Keywords

• epidemiology
• invasive pneumococcal disease
• pneumococcal vaccines
• streptococcus pneumoniae
• time-trends