A 49-year-old member asked:
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if a live vaccine gives life long immunity, why do we get booster vaccines?

1 doctor answer
Dr. James Ferguson
46 years experience Pediatrics
Varies: For some viruses (smallpox) a vaccine likely produces lifelong immunity.Others (varicella) produce immunity in only 85% with one dose,increasing to >95% with 2., and we don't know if the immunity will be life long. MMR often takes at least 2 doses and may take more. Vaccine technology has improved over the years, but we cannot replicate what nature does naturally. Lifelong is not true in all cases
Answered on Nov 10, 2014

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