PORTLAND, Ore. –A new study published in the New England Journal of Medicine this week by Oregon Health & Science University researchers suggests that timelines for vaccinating and revaccinating Americans against disease should possibly be reevaluated and adjusted. The study shows that in many cases, the established duration of protective immunity for many vaccines is greatly underestimated. This means that people are getting booster shots when their immunity levels most likely do not require it. The results are published in the November 8 edition of the journal.