Understanding Flu Viruses

graphic of flu virus

Influenza (Flu) Viruses

There are two main types of human flu viruses: types A and B. The flu A and B viruses that routinely spread in people are responsible for seasonal flu epidemics each year.

Flu A viruses can be broken down into sub-types depending on the genes that make up the surface proteins. Over the course of a flu season, different types (A & B) and subtypes (flu A) of flu circulate and cause illness.

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