Headlines - Surveillance of Severe Influenza Cases Admitted to Intensive Care as of February 26, 2014

Since November 1, 2013, 338 cases of influenza admitted to intensive care units have been reported to the InVS, including 68 new cases in week 08. The vast majority of severe cases were infected with a type A virus (95%), with the A(H1N1)pdm09 virus predominating to date (86% of the 149 subtyped type A viruses). The cases ranged in age from 1 month to 97 years (median age 59 years), and 86% of them had at least one risk factor. Among risk factors other than age, lung diseases were the most common (37%), followed by obesity with and without other comorbidities (22%), heart disease (18%), and diabetes (17%). At least 62% of cases had not been vaccinated. More than half of the cases (56%) presented with acute respiratory distress syndrome (ARDS); 7% of cases received extracorporeal membrane oxygenation (ECMO). Twenty-seven deaths were recorded. Ages ranged from 3 months to 85 years (median age 61 years). Among these deceased patients, 23 had a risk factor, 24 were infected with virus A, and none with virus B. The case fatality rate is 8%, but the vast majority of patients remain hospitalized. The proportion of severe cases without risk factors (14%) is the lowest observed since 2009, the year this surveillance system was established. The proportion of obese patients matches the values observed during the first two years of surveillance, when the A(H1N1)pdm09 virus was circulating widely. The proportion of patients with ARDS this year is similar to the rate observed in 2010–11 (68%). However, the proportion of severe cases treated with ECMO is lower than in 2010–11 (11%) and identical to last season’s data. The number of deaths is low at this time. At this stage, surveillance of severe cases does not indicate that the severity of the epidemic is greater than that observed over the past five seasons. Table 3 of the EP details the characteristics of severe cases reported in the Bourgogne and Franche-Comté regions.