RESUMO
BACKGROUND: The 2009 H1N1 influenza A virus infection pandemic was an important challenge for public health systems worldwide. MATERIAL AND METHODS: A prospective study including all patients with an influenza-like illness, with microbiological criteria for 2009 H1N1 virus, from July to December 2009 seen in the paediatric emergency department. Viral testing was performed using multiplex real-time reverse transcription polymerase chain reaction (RT-PCR). We analysed the number of visits to, and hospital admissions from, our emergency department. We compared patients with laboratory-confirmed 2009 H1N1 virus with non-confirmed ones. RESULTS: A total of 1144 patients with microbiological criteria were identified. Of these, 513 (44.8%) were admitted to hospital, 12 of them (1%) to the PICU and 3 (0.3%) died. The majority of the patients (824; 72%) had some underlying medical condition. Of the 1144 patients, 412 (36%) had RT-PCR confirmed 2009 H1N1 infection, and 732 (64%) were not confirmed. The mean age of patients with 2009 H1N1 infection was higher than those not infected (median age: 7.4 vs 4.1 years; p<.001). Laboratory-confirmed 2009 pandemic H1N1 influenza patients had more underlying high-risk conditions (OR: 2.21 [1.65-2.96]), suffered from pneumonia in less cases (OR: 0.33 [0.23-0.49]) and were admitted to hospital in less cases (OR: 0.19 [0.14-0.24]). In our emergency department, we identified an important increase in the number of visits (12%) and admissions (5.7%) compared to the previous year, 2008. CONCLUSIONS: The 2009 pandemic H1N1 influenza caused significant morbidity but the mortality was not significant. The majority of children with laboratory-confirmed 2009 H1N1 virus had uncomplicated illnesses despite the increased presence of high-risk conditions.