Abstract
The Nationwide Inpatient Sample aggregated data from approximately 20% of US hospital admissions from 1993 to 2011. Prior literature found that pneumonia admissions decreased following the introduction of the pneumococcal vaccine in 2000. The International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), codes provide information regarding pneumonia pathogens, but no studies, to our knowledge, have used these codes to analyze longitudinal trends in the pathogens documented during hospitalizations for pneumonia.