Pandemic influenza in the 2009/2010 season in central Poland: the surveillance study of laboratory confirmed cases.

We retrospectively studied confirmed cases of influenza obligatorily reported to health authorities in central Poland during the 2009/2010 season. Each case was traced and examined with a questionnaire. The samples were tested for influenza A and B by RT-PCR. A total of 561 cases of influenza, including 185 in children under 14 years old, were detected. Four hundred and eighty four people were hospitalized, including 142 children under 14. Thirty two patients died, all with pre-existing risk factors. The most common complications were pneumonia, cardiac arrest, septic shock, circulatory insufficiency, multi-organ failure and myocarditis. The majority of patients (388/484) were treated with oseltamivir. Fifty three patients were mechanically ventilated, 52 patients were given oxygen. Only 11 out of the 561 patients were immunized against seasonal influenza. In conclusion, pandemic influenza affects all age groups, but it is more common in younger patients. Pandemic influenza is becoming an emerging health risk for the Polish population.