[gibba999]

Where did you get that definition of a vaccine?

Few vaccines, historically, worked perfectly.

[a_conservative]

From the article:

> It’s important to note childhood vaccines for polio, measles, mumps, rubella and smallpox aren’t leaky; they are considered “perfect” vaccines.

[Wowfunhappy]

Some vaccines (including those) are basically perfect, but they're a minority. It also doesn't logically follow that anything which isn't perfect isn't a vaccine.