Influenza and viral pneumonia associated hospitalizations in Washington, DC

Background: The District of Columbia has consistently had less than optimal coverage of the influenza vaccine among residents 65 years or older. Since 1997, slightly more than half of those surveyed stated that they had received the influenza vaccine. Achieving the year 2010 goal of 90% of non-institutionalized adults 65 years and older immunized against influenza presents a challenge to outreach workers. Each year these high risk groups are hospitalized despite the availability of the influenza vaccine.

Objective: To determine if there are geographic clusters of residents, children under five and the elderly, hospitalized for influenza and viral pneumonia.

Methodology: The District of Columbia hospital discharge database for 1997-2004 was used to determine the number of cases of influenza and pneumonia among District residents. The data were stratified based on age, insurance status and geographic location. Spatial statistics was used to determine if the relative location and size of clusters.

Results: Of the total number of hospitalizations for influenza and viral pneumonia, the high risk groups, children under five years of age and the elderly, 65 years or older, accounted for three out of five inpatient visits. Influenza and viral pneumonia hospitalizations were also found to be prevalent in areas of lower socioeconomic status.

Conclusion: Vaccinations for influenza in the elderly in the District of Columbia are well below established public health goals. It is expected that this information will be useful in the design of outreach programs to raise the vaccine coverage in Washington, DC.