OBJECTIVETo analyze the clinical characteristics of hospitalized pediatric patients infected with 2009 H1N1 influenza.

METHODSTotally 159 children (83 male and 76 female) with influenza A (H1N1) confirmed by the real-time reverse-transcriptase-polymerase-chain-reaction assay were admitted to a special ward of Capital Institute of Pediatrics from November 2009 to January 2010. Clinical manifestations, laboratory and therapy data from the hospitalized children were collected by designed case report form and analyzed.

RESULTSOut of 159 hospitalized patients, 139 (87.4%) were under the age of 5 years and 34.0% of them had at least one underlying medical conditions. Proportions of the severe cases, pneumonia and underlying medical diseases were similar between the 78 infants and 81 older children. All of these 159 cases had influenza-like symptoms at onset and the most common presentations were fever (115 cases, 72.3%) and cough (154 cases, 96.8%). Five severe cases presented dyspnea, cyanosis and hypoxemia. The virus easily invaded into the lower respiratory tract as indicated by that 61% of the cases had findings consistent with pneumonia by X-ray and/or CT and 21.6% had bacterial co-infection. Part of them had mycoplasma pneumonia (20 cases, 27.0%) or other respiratory viruses (5 cases, 3.1%) co-infection simultaneously. The duration of fever was similar between the H1N1 virus sole infection group and the co-infection group (t = 0.975, P > 0.05), but the average course of the disease and hospitalized days of the latter group were longer than the former (t = 3.182 and 3.190, P < 0.01). The proportion of children with pneumonia in the co-infection group was significantly higher than that in the H1N1 sole-infection group (χ(2) = 4.082, P < 0.05).

CONCLUSIONSMost of the H1N1 infected pediatric patients had mild respiratory symptoms, a few of them developed severe manifestations. Dyspnea and hypoxemia were the early signals for the developing severe cases. Rational and experienced treatment with antibiotics was important addition to the antiviral therapy for those co-infected with bacteria.