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  • Hepatitis B
  • For Healthcare Personnel

I work in occupational health and have some patients who are off schedule for their 3-dose hepatitis B vaccine series. They came back for dose #2 in 4 to 6 months rather than getting it 1 month later. In this situation, what is the correct timing for dose #3? And how long must the interval be between doses before I am required to restart the series?

The minimal intervals for the 3-dose HepB vaccines are at least 4 weeks between doses #1 and #2, at least 8 weeks between doses #2 and #3, and at least 16 weeks between doses #1 and #3. Since in your cases 16 weeks or more have elapsed since dose #1, you should schedule dose #3 to be given 8 weeks after dose #2. It is not necessary to restart the series because of an extended interval between doses, no matter how long.

Last reviewed: July 21, 2023

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