Epidemiology of seasonal influenza: use of surveillance data and statistical models to estimate the burden of disease. J Infect Dis. 2006;194 Suppl

The US Centers for Disease Control and Prevention (CDC) uses a 7-component national surveillance system for influenza that includes virologic, influenza-like illness, hospitalization, and mortality data. In addition, some states and health organizations collect additional influenza surveillance data that complement the CDC’s surveillance system. Current surveillance data from these programs, together with national hospitalization and mortality data, have been used in statistical models to estimate the annual burden of disease associated with influenza in the United States for many years. National influenza surveillance data also have been used in suitable models to estimate the possible impact of future pandemics. As part of the public health response to the 2003–2004 influenza season, which was noteworthy for its severe effect among children, new US surveillance activities were undertaken. Further improvements in national influenza surveillance systems will be needed to collect and analyze data in a timely manner during the next pandemic. Over the past century, US systems to estimate the health burden associated with circulation of influenza viruses have grown from reporting of spikes in wintertime mortality in a few cities to an integrated surveillance system made up of many components, including de-tailed characterization of circulating viruses. By use of current surveillance data with national hospitalization and mortality data, models have been developed to es-timate the annual burden of influenza. In addition, models have been used to estimate the possible eco-nomic impact and health care needs of future pandem-ics, by using data available from the 3 pandemics of the 20th century. This review describes current huma