Incidence of Recurrent Invasive Pneumococcal Disease in Canada.

Importance: Recurrent invasive pneumococcal disease (rIPD) constitutes a clinically relevant proportion of all IPD cases. Improved understanding of these cases can inform priorities for prevention through vaccination. Objective: To describe the incidence of rIPD and associated risk factors in adults with a primary episode of IPD. Design, Setting, and Participants: This population-based, multicenter cohort study was performed during active surveillance for IPD in adults in Calgary and the Toronto-Peel regions of Canada from January 1, 2004, to December 31, 2022. rIPD was defined as IPD occurring 30 days or longer after a primary episode. Canadian reference laboratories performed serotyping; population data were obtained from Statistics Canada and the Alberta Interactive Health Data Application. Data were analyzed from September 3, 2024, to November 28, 2025. Main Outcomes and Measures: Incidence of rIPD over time. Risk factors for rIPD were assessed using multivariable logistic regression. Results: From 2004 to 2022, 7006 adult patients survived a primary episode of IPD, 274 (3.9%) of whom had rIPD. The median age at primary infection in patients with rIPD was 53.6 (IQR, 41.4-66.0) years; 168 patients (61.3%) were male. The incidence rate ratio (IRR) of rIPD compared with primary IPD rate in surveillance populations was highest in the first year after primary IPD (IRR, 152; 95% CI, 124-185). From 5 to 17 years after primary IPD, the IRR was 15 (95% CI, 11-20). Factors associated with recurrent disease included history of stem cell transplant or hematologic cancer (odds ratio [OR], 5.17; 95% CI, 3.35-7.98), HIV infection (OR, 4.47; 95% CI, 2.84-7.04), experiencing homelessness (OR, 1.87; 95% CI, 1.30-2.69), and alcohol use disorder (OR, 1.50; 95% CI, 1.07-2.11). Primary infection with serotype 3 (OR, 0.33; 95%, 0.16-0.67) or serotype 7F (OR, 0.42; 95% CI, 0.21-0.87), and being 65 years or older (OR, 0.55; 95% CI, 0.34-0.90) were associated with reduced odds of rIPD. At the primary episode, 4812 of 5470 patients (88.0%) were eligible for pneumococcal vaccine, and 1344 of 4812 (27.9%) had been vaccinated. Of patients with known vaccine status between the first and second episodes, 167 of 229 (72.9%) were eligible for vaccine and only 37 of 167 (22.2%) received one. Conclusions and Relevance: In this cohort study, the risk of rIPD was higher than the risk of primary IPD throughout 17 years of follow-up. Most patients with primary IPD had indications for pneumococcal vaccine but were unvaccinated. These findings suggest that patients with IPD should be prioritized to receive recommended vaccination doses.