The third Hepatitis B vaccine dose is given after how long following the second dose?

• A. One month after second dose
• B. Two months after second dose
• C. Three months after second dose
• D. Six months after second dose

Answer: (D)

The question tests how the Hepatitis B vaccination series is spaced to build durable protection. After the first dose primes the immune system and the second dose boosts that response, waiting six months after the second dose before giving the third allows the immune system to mature the memory and produce a stronger, longer-lasting antibody response. Shorter intervals after the second dose (one, two, or three months) don’t give enough time for that mature boost and may result in less durable protection. Six months after the second dose aligns with completing the primary series in a way that optimizes long-term immunity.