Twinrix Vaccination Administration Schedule
Twinrix should be administered in a standard 3-dose series at 0,1, and 6 months for adults aged 18 years and older, with an alternative accelerated 4-dose schedule available for those requiring rapid protection. 1
Standard Administration Schedule
Primary schedule: 3 doses administered at:
- First dose: Day 0 (initial visit)
- Second dose: 1 month after first dose
- Third dose: 6 months after first dose 1
Route of administration: Intramuscular injection into the deltoid muscle 1
Dose: Each dose contains 720 EL.U. of hepatitis A antigen (half of the HAVRIX adult dose) and 20 mcg of recombinant hepatitis B surface antigen protein (same as ENGERIX-B adult dose) 1
Alternative Accelerated Schedule
For individuals requiring rapid protection (e.g., travelers or those with imminent exposure risk):
- Accelerated 4-dose schedule:
This accelerated schedule provides quicker initial protection but requires the 12-month booster to ensure long-term immunity.
Key Considerations
Age restrictions: Twinrix is only licensed for use in persons aged ≥18 years in the United States 1
Immune response: After completing the standard 3-dose series, antibody responses to both hepatitis A and B antigens are equivalent to those achieved when single-antigen vaccines are administered separately 1, 3
Long-term protection: Studies show antibody persistence for at least 10 years after primary vaccination with Twinrix 4
Storage requirements: Store at 2°C-8°C (35.6°F-46.4°F); do not freeze 1
Preservative: Contains 2-phenoxyethanol as a preservative 1
Special Populations
Older adults: Twinrix is effective in adults over 40 years of age, though immune response may be somewhat lower than in younger adults 5
Immunocompromised patients: May require post-vaccination serologic testing to confirm protection 6
High-risk groups: For populations at high risk of non-completion (e.g., injection drug users), the accelerated schedule may improve compliance, though evidence for superior completion rates is limited 2
Contraindications and Precautions
Contraindications: Severe allergic reaction to a previous dose or vaccine component
Pregnancy: No evidence of risk, but benefits should outweigh potential risks
Completion Importance
Completing the full vaccination series is critical for establishing long-term protection against both hepatitis A and hepatitis B infections. Partial vaccination may not provide adequate immunity, particularly against hepatitis B.