Incidence of Recurrent Invasive Pneumococcal Disease in Canada

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.

To describe the incidence of rIPD and associated risk factors in adults with a primary episode of IPD.

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.

Incidence of rIPD over time. Risk factors for rIPD were assessed using multivariable logistic regression.

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.

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.