The genetic change that enables a flu strain to jump from one animal species to another, including humans, is called antigenic shift. Antigenic shift can happen in three ways:
The new strain may further evolve to spread from person to person. If so, a flu pandemic could arise.
Credit: This image is in the public domain. Please credit the National Institute of Allergy and Infectious Diseases (NIAID). Illustrator: Links Studio. Download: high resolution version of the Antigenic Shift illustration.
View Antigenic Drift
back to top
Last Updated January 14, 2011