[shajith]

"In reality, for a vaccine to be effective, the portion of the population that needs to receive that vaccination is significantly less than 100%."

I'm curious to know if there have been results that show what sort of percentages of vaccination are needed to be safe from specific diseases. I presume this will vary between diseases as well as demographics.

[henrikschroder]

Yes, it's called Herd Immunity, a quick glance at the Wikipedia article show some percentages for common diseases.

http://en.wikipedia.org/wiki/Herd_immunity