How flu changes within human body may hint at evolution of global trends

Controlling the spread of flu means dealing with ongoing evolution

Evolution is usually very slow, a process of change that takes thousands or millions of years to see.

But for influenza, evolution is fast and deadly. Flu viruses change rapidly to escape the body’s defences. Every few years, new variants of flu emerge and cause epidemics around the world.

Controlling the spread of flu means dealing with this ongoing evolution. Each year, experts from the World Health Organization (WHO) must make their best guess about how the virus will change in order to choose which flu strains to include in the annual vaccine.

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