Headlines - Monitoring Severe Cases of Influenza

When describing a disease, we focus not only on the number of cases but also on its severity and preventability. This is true for influenza, where, among the millions of annual cases in France, a portion consists of severe cases that we seek to prevent by vaccinating people at risk of developing these severe forms. In 2009, during the influenza pandemic, the InVS implemented a specific surveillance system for severe cases, defined as any case admitted to an intensive care unit with probable or biologically confirmed influenza. The Cire dedicated a health surveillance bulletin to this surveillance in Burgundy and Franche-Comté. It confirms variations across different winters in the profile of individuals affected by severe forms of influenza, variations linked to the dominant virus. Comparison with the PMSI indicates that this specific surveillance is comprehensive. It also confirms that admission to intensive care involves only a portion of patients (ranging from 1.1% to 9.5% depending on the year and region) among the hundreds of patients hospitalized for influenza (ranging from 113 to 860 per region per year). Admission to intensive care for influenza leads to a few direct deaths each year in every region (ranging from 2 to 7). Finally, only one-tenth of patients hospitalized for influenza have visited the emergency department.