Sure, I hear a lot of talk about flu shots and flu seasons…but, what happened to naming the flu, like Hong Kong flu, or Swine flu? Do we do this anymore? And, why did we used to? - Jinx
It’s still done, in a way, Jinx. This diagram shows how new 'flu strains are named after their type, origin, year isolated, etc.
Why? It tells the strains apart in a rapidly evolving virus.
the “flu” is short for influenza, an italian word for influence. In the Middle Ages, people believed that you got sick because you were exposed to a bad influence, most likely infested damps, or poisoned air. They didn’t know anything about bacteria or viruses (the flu is a virus).
The term got used widely, and as Ice Wolf posted, different strains with a different virulence were given different names, mostly according to the place where it first rears its head.
[ul]It was giving southeastern asia a bad name. 
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We’ve learned more about how the virus works, and what exactly the differences are between various strains, so we now have a more precise and specific nomenclature system.