Health A-Z: Influenza


Influenza (the flu) is a respiratory infection. It is caused by the influenza virus. Influenza typically is spread by air or by direct contact from one person to another. Influenza virus is very contagious. Most influenza cases occur during epidemics. Epidemics peak during the winter months. A particularly widespread and severe epidemic is called a pandemic.


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Ah-choo! Cold and Flu Season - Health A-Z

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    The Patient Education Center provides multimedia access to reliable and relevant medical information at and beyond the point of care. Our content is developed exclusively by Harvard Health Publications, the media and publishing division of the Harvard Medical School of Harvard University, and distributed by Health Media Network.