Do I need to restart the hepatitis B (Hep B) vaccination series or can I continue with the next dose after receiving the first dose about a year ago without a hepatitis B titer?

Hepatitis B Vaccination with Interrupted Schedule

You do not need to restart the hepatitis B vaccination series after receiving the first dose a year ago - you should simply continue with the second dose today and complete the series with a third dose later. 1

Understanding Interrupted Hepatitis B Vaccination Schedules

The Advisory Committee on Immunization Practices (ACIP) clearly states that when the hepatitis B vaccine schedule is interrupted, the series does not need to be restarted regardless of the time elapsed between doses 1, 2. This is a key point that applies directly to your situation.

For your specific case:

• Since you received the first dose about a year ago
• You should receive the second dose now (today)
• The third dose should be administered:
  • At least 8 weeks after the second dose
  • At least 16 weeks after the first dose 1

Minimum Intervals Between Doses

To ensure optimal protection, follow these minimum intervals:

• Between 1st and 2nd doses: at least 4 weeks
• Between 2nd and 3rd doses: at least 8 weeks
• Between 1st and 3rd doses: at least 16 weeks 1, 2

Since you've already waited a year since your first dose, the minimum interval between the first and second doses has been well exceeded. After receiving your second dose today, you'll need to wait at least 8 weeks before getting the third dose.

Effectiveness of Delayed Schedules

Research supports that delayed intervals between hepatitis B vaccine doses do not diminish effectiveness. A 2022 study of nearly 23,000 adults found that flexibility in the timing of the second and third doses did not necessitate restarting the vaccination series 3. In fact, some studies suggest that longer intervals between doses may actually result in higher antibody levels 4, 5.

Important Considerations

1. No need for hepatitis B titer testing: For most healthy adults, routine post-vaccination serologic testing is not recommended 2.

2. Injection site matters: For optimal immune response, ensure the vaccine is administered in the deltoid muscle (upper arm), not the buttock 6.

3. Documentation: Keep records of your vaccination dates to ensure proper completion of the series.

Completion Schedule

Your recommended schedule moving forward:

• Second dose: Today
• Third dose: At least 8 weeks after today's dose (but can be given later if needed)

Common Pitfalls to Avoid

1. Restarting unnecessarily: Many people incorrectly believe they need to restart the series after a delay, which is not the case 1, 2.

2. Insufficient intervals: While you can't get the doses too far apart, getting them too close together (less than the minimum intervals) can reduce effectiveness 1.

3. Missing the final dose: The full three-dose series is needed for optimal long-term protection, so be sure to complete all doses 2.

By following these guidelines, you can effectively complete your hepatitis B vaccination series without restarting, ensuring protection against hepatitis B infection.