CLINICAL, VIROLOGICAL AND EPIDEMIOLOGICAL ASSESSMENT OF 2009 INFLUENZA A (H1N1) PANDEMIC IN A BELGIAN UNIVERSITY HOSPITAL

Background: Recommendations were applied before and during the Belgian pandemic (2009) H1N1 influenza wave at a university hospital (420 beds), for optimizing isolation processes and therapeutic management of possible and confirmed infected cases. Methods: All patients presenting to the Emergency Department (ED) between August 1st and December 31st 2009 were screened for ILI symptoms, and were isolated for clinical assessment in case of positive screening. Patients categorized as possible influenza cases and who required hospitalization were isolated in dedicated wards. Specific diagnostic algorithms were implemented. Medical charts were retrospectively reviewed and matched with results of the microbiology laboratory. Patient's characteristics were analyzed, the contribution of laboratory diagnosis on therapy and lengh of stay (LOS) in isolation was also assessed. Results: 310 patients out of 6068 had a positive screening for ILI, of these, 265 were retained as possible influenza cases and 139 required hospitalization. Twenty-eight children (8 requiring hospitalization) and 20 hospitalized adult patients had confirmed influenza infection. Five adult patients were admitted to the intensive care unit (ICU), 3 requiring extracorporeal membrane oxygenation (ECMO). There was no death related to the new influenza strain. The majority of confirmed patients were diagnosed during the Belgian epidemic wave, with a sensitivity of antigen detection of 50% in children and 35% in adults comparatively to real-time PCR (RT-PCR). Conclusions: The impact of (2009) H1N1 pandemic influenza remained limited, except for ICU patients requiring ECMO. Implementation of screening, isolation, and virological diagnosis processes led to significant improvement of patient management.