Influenza Burden Assessment in the United States, July1997 - up to April 2009

Burden of Influenza in the United States, July 1997 up to April 2009

The study will assess the burden of severe influenza outcomes by age, risk status, and influenza subtype, in order to create a profile of the burden of influenza-related morbidity and mortality in United States from July 1997 to April 2009.

This epidemiological study is a modelling of time series retrospectively extracted from multiple databases. Data will be extracted from existing electronic healthcare databases.

Inclusion Criteria:

• Recorded in the US NIS hospitalization data or the US National Vital Statistics System (NVSS) mortality data with a pre-specified diagnostic code.

Exclusion Criteria:

• Missing data in the following fields: age, primary discharge diagnosis, admission month (NIS) /month of death (NVSS), and status at discharge (alive / dead).