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|Wed, 03-03-2010 - 6:26pm|
I am confused about how heard immunity works. I read somewhere that some vaccines only last 10 years. Yet I don't remember the doctor asking me to get vaccinated on some of these vaccines and I believe that most adults are not re vaccinated as adults. From what I understand you need about a 80% or something amount of people to be vaccinated to have a heard immunity. If that is so then how come these diseases are not coming back or am I completely off base here.