Pneumococcal Vaccination as Cardiovascular and Cardiorespiratory Prevention in Adults with Heart Disease

Background/Objectives: Streptococcus pneumoniae is a major cause of community-acquired pneumonia and invasive pneumococcal disease, particularly in older adults and people with cardiovascular disease. Pneumococcal infection may precipitate heart failure, arrhythmias, myocardial infarction, stroke, functional decline, hospitalization, and death. This review examines pneumococcal disease as a cardiovascular stressor, the effectiveness of adult pneumococcal vaccination, and the comparative clinical relevance of higher-valency conjugate vaccines. Methods: We conducted a narrative review of randomized trials, phase 3 immunogenicity and safety studies, real-world effectiveness analyses, observational cardiovascular cohorts, meta-analyses, epidemiological surveillance reports, regulatory documents, and current European, U.S., and Spanish recommendations. Results: Clinical evidence supports protection against vaccine-type invasive pneumococcal disease and pneumococcal pneumonia. Associations between pneumococcal vaccination and lower myocardial infarction risk derive predominantly from observational studies and do not establish causality; a reduction in cardiovascular events remains unproven. The 23-valent polysaccharide vaccine is an older, unconjugated platform that induces a T-cell-independent response without the immunological memory produced by conjugate vaccines; therefore, a higher nominal valency does not necessarily imply greater or more durable clinical effectiveness. PCV20 and PCV21 are higher-valency conjugate vaccines with partially overlapping non-nested serotype compositions. Both have adult regulatory indications in Spain, but their evidence bases differ: PCV20 has phase 3 immunogenicity and safety evidence plus emerging real-world effectiveness data, whereas PCV21 currently has a broad phase 3 immunogenicity and safety program. No head-to-head clinical-outcome study has established superior effectiveness of either vaccine. Differences in estimated serotype coverage reflect epidemiological overlap and do not directly quantify clinical protection. Spanish serotype epidemiology is highly dynamic, with persistent adult disease caused by serotypes included in each formulation and recent increases in selected legacy serotypes retained in PCV20. A serotype-specific association between serotypes 3 and 9N and cardiovascular events has been reported in one invasive-disease cohort but was not reproduced in a larger pneumococcal pneumonia cohort. Conclusions: Pneumococcal vaccination should be integrated into cardiovascular care for eligible adults to prevent pneumococcal disease. Any additional benefit in preventing myocardial infarction or other cardiovascular events, including long-term complications, remains uncertain. Vaccine selection should follow official recommendations and consider age, previous vaccination, regional epidemiology, serotype-associated disease burden and severity, antimicrobial resistance, and availability rather than valency or immunogenicity alone.