PA grad student asked:


I have had the Hepatitis B Series of vaccinations twice - once in 1998 and again in 2006. Each time I was sure to go by the posted quidelines of when all 3 shots should be administered - however twice the blood work has came back that i was not immunte. Once in 2006 - hence the second series and again last week. I will be working in public health and will likely get a third series of vaccinations - but was curious if anyone knew why this may be happening.

Julie