3. Study design The design is a prospective cohort study in which response to pneumococcal vaccination and immune function after CAP with S. pneumoniae will be investigated. Patients who were included in the Ovidius or Triple-P study and diagnosed with pneumococcal pneumonia (with cultures, urine antigen test or serology) will be included. The control group will consist of patients who were included in the Ovidius or Triple-P study and diagnosed with community acquired pneumonia with another pathogen.