Burden of Invasive Pneumococcal Disease and Community-Acquired Pneumonia in Adults: Significant Adverse Outcomes and Costs beyond Direct Treatment

INTRODUCTION: Infectious diseases, including invasive pneumococcal disease (IPD) and community‑acquired pneumonia (CAP), are associated with severe burden and adverse outcomes beyond the acute episode. The comprehensive burden has not been previously assessed in Finland. Here, we characterized adult patients (≥ 18 years) with IPD and CAP in Finland, followed them up for adverse outcomes, and estimated the economic burden. METHODS: This is a nationwide registry-based cohort study, including 2894 adults with laboratory-confirmed IPD; 129,203 adults with inpatient CAP; 126,314 adults with outpatient CAP; and their 760,748 age-sex-region-matched controls. RESULTS: Overall, 40-60% of the patients had at least one predefined medical risk factor; however, a substantial proportion (34-40%) of patients aged ≥ 65 years did not have any predefined risk factors. Patients aged ≥ 65 years with IPD and inpatient CAP had the highest rates of adverse outcomes, including recurrence, admission to institutional care, and acute myocardial infarction. IPD and CAP were associated with considerable attributable healthcare costs, including direct disease-specific costs, increased all-cause costs above them, and indirect costs due to work absenteeism. Serotypes included in the pneumococcal conjugate vaccines (PCVs) PCV13, PCV20, and PCV21 covered 43.0%, 61.1%, and 77.7% of IPD cases, respectively, in the age group ≥ 65 years in 2023-2024. CONCLUSIONS: IPD and CAP are associated with substantial morbidity, mortality, and economic burden, particularly among adults aged ≥ 65 years. In this age group, pneumococcal disease alone accounted for ~€39 million annually in total costs (inflated to 2023 values). As many older patients had no predefined medical risk factors, age‑based pneumococcal vaccination and broader use of higher‑valency conjugate vaccines seem warranted to reduce disease burden and societal costs.