Summary

The most frequent complication of A (H1N1) influenza and the leading cause of death was pneu-monia with a primary viral or mixed viral and bacterial etiology. 182 patients had died because of a pandemic influenza in Poland by 31st July 2010. A retrospective study of 6 fatal cases of pandemic influenza, aged 23-41, including 3 women, hospi-talised between November 2009 and February 2011 in different Polish medical centres. We present the clinical course of 6 late diagnosed cases of A (H1N1) influenza. All patients presen-ted typical flu-like symptoms in the beginning. 4/6 patients had severe disease risk factors: pre-gnancy, arthritis, Wegener granulomatosis and obesity. All patients were seen by doctors, no one had received antiviral therapy, 4/5 were treated with antibiotics before they were hospitalized. One patient had nosocomial infection. Patients were admitted to the hospital on the 3rd to 8th day of the disease. They received oseltamivir treatment on the 4th to 9th day. All patients developed pneumo-nia complicated by acute respiratory distress syndrome. Death appeared between the 4th and 27th day after the onset of symptoms. Autopsies were performed in 5 cases and revealed haemorrhagic pneumonia in 2 patients. Delayed diagnosis and antiviral treatment initiation has a significant impact on mortality in A (H1N1