The Influence of Influenza and Pneumococcal Vaccines on Community-Acquired Pneumonia (CAP) Outcomes Among Elderly Patients.

Elderly are at high risk for hospitalization for community-acquired pneumonia (CAP), especially due to Streptococcus pneumoniae, and seasonal influenza viruses. Data suggest PPV23's influence on various CAP-related outcomes among the elderly may depend upon how many years have elapsed since they received this vaccine. PPV23's protection against invasive pneumococcal disease and CAP hospitalizations are often limited to moderately ill elderly, who are less than 75 years old, or female. PCV13 demonstrates broad protection against a variety of CAPs, but ultimately, its influence on their outcomes among the elderly may be limited by herd immunity from PCV7 use. Influenza vaccine's indirect protective effect against all-cause and non-invasive pneumococcal CAP in the elderly is difficult to ascertain. The use of both PPV23 and influenza vaccine shortens length of stay in hospitalized elderly with CAP, but whether that benefit would be realized in the presence of herd immunity is unknown.