Abstract
Influenza is a well-known viral disease of the respiratory tract. It must be distinguished from influenza-like illnesses and other acute respiratory infections.
Influenza may have a complicated course, with some cases requiring hospitalization and initiation of antiviral therapy. Influenza complications are divided into pulmonary and extrapulmonary.
Complications can further be divided into primary (caused by an influenza virus) and secondary (caused by secondary bacterial infection). Prevention of influenza is both passive (maintaining personal hygiene) and active (vaccination).