Intensive care unit surveillance of influenza infection in France: the 2009/10 pandemic and the three subsequent seasons

Abstract

During the 2009/10 pandemic, a national surveillance system for severe influenza cases was set up in France. We present results from the system's first four years. All severe influenza cases admitted to intensive care units (ICU) were reported to the Institut de Veille Sanitaire using a standardised form: data on demographics, immunisation and virological status, risk factors, severity (e.g. acute respiratory distress syndrome (ARDS) onset, mechanical ventilation, extracorporeal life support) and outcome. Multivariate analysis was performed to identify factors associated with ARDS and death. The number of confirmed influenza cases varied from 1,210 in 2009/10 to 321 in 2011/12. Most ICU patients were infected with A(H1N1)pdm09, except during the 2011/12 winter season when A(H3N2)-related infections predominated. Patients' characteristics varied according to the predominant strain. Based on multivariate analysis, risk factors associated with death were age ≥ 65 years, patients with any of the usual recommended indications for vaccination and clinical severity. ARDS occurred more frequently in patients who were middle-aged (36-55 years), pregnant, obese, or infected with A(H1N1)pdm09. Female sex and influenza vaccination were protective. These data confirm the persistent virulence of A(H1N1)pdm09 after the pandemic and the heterogeneity of influenza seasons, and reinforce the need for surveillance of severe influenza cases.

Overview of three influenza seasons in Georgia, 2014–2017

“…A fatal outcome was predominantly associated with A/H1N1pdm09 infection and patients in the age group 30-64 years had the highest probability of a fatal outcome. Our data are consistent with findings from other countries showing that adults were at higher risk of death than younger patients when infected with A (H1N10pdm09 viruses [25][26][27][28]. The vast majority of fatal cases suffered with at least one chronic condition, with cardiovascular and neurological disorders being the leading comorbidities.…”

Predictors of Hospitalization and Admission to Intensive Care Units of Influenza Patients in Serbia through Four Influenza Seasons from 2010/2011 to 2013/2014

“…Furthermore, infection with virus influenza A (H3) was a protective factor, independently associated with admission to hospital without ICU. A French study reported similar findings for infection with A (H3N2) (17).…”

Estimating burden of influenza‐associated influenza‐like illness and severe acute respiratory infection at public healthcare facilities in Romania during the 2011/12‐2015/16 influenza seasons

“…Our results suggest that influenza is associated with substantial morbidity in terms of primary care attendances due to ILI and hospitalizations T A B L E 1 Influenza by (sub)type, ILI and catchment population of the sentinel surveillance system by age in Romania in 2011/12-2015/16 influenza seasons 20 and in Greece, during the 2010/2011 (post-pandemic) season, the CFP was 39%. 21 This could be explained by more patients being recruited in critical condition, when they were more likely to die, while others, less severe, might not have been captured; however, this does not explain the large variability between seasons.…”