Google "herd immunity." Well-recognized in the medical-scientific community.
FWIW we *are* seeing whooping cough clusters in the first world because of failing herd immunity caused partly by parent choices but also by vaccine failure. This makes it even more important to get vaccination levels as high as possible. Whooping cough can kill kids including those too young to be immunized, so herd immunity protects them too.
If you are concerned your family physician will have good information about vaccination including risks and there is good stuff on the CDC site.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
