What is the recommended use and schedule for Twinrix (Hepatitis A and Hepatitis B vaccine)?

Twinrix Vaccination: Recommended Use and Schedule

Twinrix, the combined hepatitis A and hepatitis B vaccine, should be administered as either a standard 3-dose schedule at 0,1, and 6 months or an accelerated 4-dose schedule at days 0,7,21-30 followed by a booster at 12 months for adults requiring protection against both viruses. 1

Indications for Twinrix Vaccination

Twinrix is recommended for adults seeking protection from both hepatitis A virus (HAV) and hepatitis B virus (HBV) infections, particularly those with the following risk factors:

Hepatitis A Risk Groups:

• Men who have sex with men
• Injection or non-injection drug users
• Persons working with HAV in laboratory settings or with infected primates
• Persons with chronic liver disease
• Persons who receive clotting factor concentrates
• Travelers to countries with high or intermediate HAV endemicity
• Persons anticipating close contact with international adoptees 1

Hepatitis B Risk Groups:

• Sexually active persons not in long-term monogamous relationships
• Persons seeking evaluation/treatment for STDs
• Current or recent injection drug users
• Men who have sex with men
• Healthcare personnel exposed to blood/body fluids
• Persons with diabetes (especially <60 years)
• Persons with end-stage renal disease, HIV, or chronic liver disease
• Household contacts/sex partners of HBsAg-positive persons
• International travelers to regions with high/intermediate HBV prevalence 1

Vaccination Schedules

Standard Schedule:

• 3 doses at 0,1, and 6 months 1

Accelerated Schedule:

• 4 doses at days 0,7,21-30, with a booster at 12 months
• Particularly useful for travelers needing protection within 1 month 1, 2

Dosage Information

• Adult formulation (≥18 years): 20 μg HBsAg and 720 ELU HAV antigen per 1.0 mL dose 1

Efficacy and Immunogenicity

• Anti-HAV seropositivity rates: 96.2-100%
• Anti-HBs seroprotection rates: 82-100%
• Antibody persistence up to 15 years 3
• One month after completion of the standard schedule, nearly all vaccinees develop protective antibodies against both viruses 4
• Effective in older adults (>40 years) when administered on the standard schedule 5

Special Considerations

Pregnancy:

• For pregnant women requiring hepatitis vaccination, monovalent vaccines (Engerix-B, Recombivax HB) are preferred over Twinrix due to limited safety data in pregnancy 1

Interrupted Schedules:

• If the vaccination schedule is interrupted, the series does not need to be restarted
• For a 3-dose series interrupted after the first dose, administer the second dose as soon as possible
• The second and third doses should be separated by ≥8 weeks
• The final dose must be administered ≥8 weeks after the second dose and ≥16 weeks after the first dose 1

Common Pitfalls to Avoid

1. Incomplete vaccination series: Many high-risk populations, particularly injection drug users, fail to complete the full vaccination schedule, resulting in insufficient immunity 6
2. Incorrect dosing intervals: The minimum interval between first and second doses is 4 weeks; doses given too close together may result in suboptimal immune response 1
3. Using accelerated schedule without the 12-month booster: The booster dose is critical for long-term protection when using the accelerated schedule 2
4. Assuming immediate protection: Maximum protection occurs after completing the full series; risk reduction counseling should continue during the vaccination period 1

Twinrix offers the convenience of a single vaccine providing dual protection, potentially improving compliance and reducing administration costs compared to separate hepatitis A and B vaccines 4.