If the hepatitis B (HBV) vaccine was given on a specific date, when are the next vaccination doses scheduled?

Hepatitis B Vaccine Dosing Schedule

If the first dose of hepatitis B vaccine was given on a specific date, the second dose should be administered 1 month later (minimum 4 weeks), and the third dose should be given 6 months after the first dose (minimum 16 weeks from dose 1 and at least 8 weeks after dose 2). 1

Standard Three-Dose Schedule

The most commonly used schedule follows a 0,1, and 6 months pattern: 1, 2, 3

• Second dose: Given 1 month after the first dose (minimum interval: 4 weeks) 1
• Third dose: Given 6 months after the first dose (minimum interval: 16 weeks from first dose AND at least 8 weeks after second dose) 1

Minimum Dosing Intervals - Critical to Remember

The final dose must satisfy BOTH of these requirements: 1

• At least 8 weeks after the second dose
• At least 16 weeks after the first dose

For infants specifically: The final dose should not be administered before 24 weeks of age, regardless of when earlier doses were given 1, 3

Alternative Acceptable Schedules

While the standard 0,1,6-month schedule is preferred, alternative schedules produce similar seroprotection rates: 3

• 0,2, and 4 months 3
• 0,1, and 4 months 3
• Accelerated schedule (Engerix-B): 0,1,2, and 12 months for rapid protection 3

The CDC notes that longer intervals between the last two doses (4-12 months) result in higher final antibody titers, though protection remains excellent with standard timing. 1, 4

If the Schedule is Interrupted

Never restart the series - this is a critical pitfall to avoid. 1, 3

• If interrupted after the first dose: Give the second dose as soon as possible, then give the third dose at least 8 weeks after the second dose 1
• If only the third dose is delayed: Administer it as soon as convenient 1
• The series does not need to be restarted regardless of how much time has elapsed 1

Grace Period for Early Doses

Doses administered ≤4 days before the minimum interval are considered valid and do not need to be repeated. 1

Expected Protection Timeline

Understanding when protection develops helps contextualize the schedule: 3

• After dose 1: 30-55% achieve protective antibody levels
• After dose 2: 75% achieve protection
• After dose 3: >90% achieve protection

The third dose acts as a crucial booster, providing optimal long-term immunity that persists for >30 years. 1, 3

Special Population Considerations

Infants born to HBsAg-positive mothers require a modified approach: 2, 5

• First dose within 12 hours of birth plus HBIG at a separate site
• Second dose at 1-2 months
• Third dose at 6 months
• Post-vaccination testing at 9-15 months for HBsAg and anti-HBs

Hemodialysis patients and immunocompromised adults need higher doses (40 μg) at 0,1, and 6 months with annual anti-HBs testing and booster doses when levels fall below 10 mIU/mL. 2, 3