Investigators in the Division of Infectious Diseases and the Division of Hospital Medicine of The George Washington University Medical Center are carrying out a study to determine if hospitalized patients receiving the polyvalent pneumococcal vaccine during an acute illness develop an adequate antibody response. The study group will consist of individuals diagnosed with pneumonia and admitted to the Medicine ward under the Pneumonia Core Measure Protocol, which assigns appropriate patients for vaccination based on the current guidelines from the Advisory Committee on Immunization Practices (ACIP).

Inclusion Criteria:

• Males or female patients ages 18 or older
• Diagnosis of pneumonia requiring hospitalization
• Admission to the Medicine Ward under the Pneumonia Core Measure protocol
• Eligible to receive standard of care pneumococcal vaccine by the treating physician
• Able to receive an injection
• Able to provide informed consent

Exclusion Criteria:

• Preexisting history of immunosuppression, to include any of the following: HIV/AIDS, Chronic corticosteroid use, Malignancy requiring myeloablative chemotherapy, Hematologic malignancy, History of solid organ or stem cell transplant
• Pregnancy
• Receipt of pneumococcal vaccine within the last 5 years
• Prior history of hypersensitivity reaction to the vaccine
• Unable to return for follow-up testing

Individuals who have been admitted to the Medicine Ward under the Pneumonia Core Measure Protocol as stated by the Joint Commission, and who receive the polyvalent pneumococcal vaccine as an inpatient as indicated by ACIP guidelines.