Iqraabout 1 year ago

Causes of flu

The influenza virus causes flu. Influenza A, B and C are the most common types that infect people. Influenza A and B are seasonal (most people get them in the winter) and have more severe symptoms. Influenza C doesn’t cause severe symptoms and it’s not seasonal — the number of cases stays about the same throughout the year. H1N1 (“swine flu”) and bird flu are both subtypes of influenza A.