Pandemic influenza A(H1)pdm09 in hospitals and intensive care units - results from a new hospital surveillance, Germany 2009/2010.

OBJECTIVES: The pandemic influenza A(H1)pdm09 (PI) was introduced to Germany in April 2009. The Robert Koch Institute (RKI) implemented a nationwide voluntary hospital sentinel surveillance for to assess the burden and severity of PI.
SETTING: Three modules were offered: a hospital module collected aggregated data from all hospital units on admissions and fatalities with and without PI; an intensive care module data on admissions, patient-days, and ventilated patient-days with and without PI; and a case-based module retrieved clinical patient data of PI cases. A in-patient with a PCR confirmation was defined as a PI case. Descriptive, trend, uni-, and multivariable analysis were performed.
RESULTS: Between week 49/2009 and 13/2010, the hospitals reported 103 (0.07%) PI cases among 159181 admissions and 59/16728 (0.35%) PI-related admissions in intensive care units (ICUs). The weekly average incidence decreased in hospitals by 21.5% and in ICUs by 19.2%. In ICUs, 1848/85559 (2.2%) patient-days were PI-related, 94.8% of those with mechanical ventilation. Case-based data on 43 recovered and 16 fatal PI cases were reported. Among recovered, 61% were admitted to ICUs, 51% were mechanically ventilated, and 16% received extracorporeal membrane oxygenation (ECMO). All fatal cases were admitted to ICUs and received mechanical ventilation, 75% ECMO. Fatal outcome was rather associated with complications than with underlying medical conditions.
CONCLUSION: The surveillance started shortly after the PI peak, which explains the small number of PI cases. The burden of PI disease was low, but higher in ICUs with a high proportion of severe cases needing ventilation and ECMO treatment. A continuous hospital surveillance system could be helpful to measure the burden of severe community-acquired infections.