Inpatient Influenza Surveillance

Influenza vaccination has been recommended for all persons greater than or equal to age 65, recent studies have questioned the efficacy of the vaccine in the aging population. The willingness to test new vaccines depends on a convincing demonstration of a significant burden of disease despite current vaccine policies. If comprehensive surveillance could be performed in a well defined population of adults over 50 years of age hospitalized with acute respiratory illness or fever, the precise burden of influenza illness in this age group could be determined and the risk factors associated with influenza infection established. This study will be a one year pilot study. Study participants will include 350 adults greater than and equal to 50 years of age hospitalized at Vanderbilt University or a local community hospital, Baptist Hospital, with acute respiratory symptoms or fever. The purpose of the study is to determine the feasibility of conducting a larger surveillance study in several other hospitals. Specific aims are: 1) to perform population-based surveillance to determine the etiology and burden of acute viral respiratory diseases or fever among hospitalized adults greater than or equal to 50 years of age and 2) to identify risk factors associated with hospitalization for vaccine-preventable respiratory disease in adults greater than or equal to 50 years of age. During November 2006 through April 2007, recruitment will occur 2 days per week and will increase to 4 days per week during the defined influenza season based on local surveillance. Following informed consent, there will be 3 parts to data collection: (1) series of brief questions; (2) one nasal and one throat swab will be collected and; (3) chart abstractions performed after discharge. Nasal and throat swabs will be tested for influenza A and B viruses by both viral culture, rapid antigen testing, and Real-Time Reverse-Transcriptase PCR (RTrtPCR) analysis. The primary endpoint of the study is the incidence of hospitalizations due to influenza virus by age, sex, and race in adults greater or equal to than 50 years of age. This study is linked to DMID protocol 06-0092.