• Vaccines

Twinrix Generic Name & Formulations

General Description

Hepatitis A inactivated 720 ELISA Units (EL.U.), hepatitis B surface antigen (recombinant) 20mcg; per mL; susp for IM inj; aluminum adsorbed; contains trace amounts of formalin, neomycin, yeast protein; preservative-free.

How Supplied

Single-dose prefilled syringes—10


Store refrigerated between 2° and 8° C (36° and 46° F). 
Do not freeze; discard if the product has been frozen.


Generic Availability


Mechanism of Action

The presence of antibodies to HAV (anti-HAV) confers protection against hepatitis A disease. However, the lowest titer needed to confer protection has not been determined. Antibody concentrations ≥10mIU/mL against HBsAg are recognized as conferring protection against hepatitis B virus infection.

Twinrix Indications


Hepatitis A and hepatitis B immunization.

Twinrix Dosage and Administration


≥18yrs: 1 inj IM in deltoid region at 0-, 1-, and 6 months. Alternate 4-dose schedule: 1 inj IM in deltoid region at 0-, 7-, and 21 to 30-days followed by booster dose at month 12.


<18yrs: not established.

Twinrix Contraindications

Not Applicable

Twinrix Boxed Warnings

Not Applicable

Twinrix Warnings/Precautions


May defer in acute febrile illness or active infection. Immunocompromised. Risk of syncope. Have epinephrine (1:1000) inj available. Latex allergy (prefilled syringes). Pregnancy. Nursing mothers.


Limitations of Vaccine Effectiveness

  • Hepatitis A and hepatitis B have relatively long incubation periods.
  • The vaccine may not prevent hepatitis A or hepatitis B infection in individuals who have an unrecognized hepatitis A or hepatitis B infection at the time of vaccination.
  • Vaccination with Twinrix may not protect all individuals.

Pregnancy Considerations

There are no adequate and well-controlled studies of Twinrix in pregnant women in the US.

Available data do not suggest an increased risk of major birth defects and miscarriage in women who received Twinrix within 28 days prior to conception or during pregnancy.

Nursing Mother Considerations

There is no information regarding the presence of Twinrix in human milk, the effects on the breastfed child, or the effects on milk production.

Consider the health benefits of breastfeeding along with the mother’s clinical need for Twinrix and any potential adverse effects on the breastfed child from Twinrix or from the underlying maternal condition.

Pediatric Considerations

Safety and effectiveness in pediatric patients <18 years have not been established.

Geriatric Considerations

Clinical studies of Twinrix did not include sufficient numbers of participants aged 65 years and older to determine whether they respond differently from younger participants.

Twinrix Pharmacokinetics

See Literature

Twinrix Interactions


Concomitant immune globulin: give with separate syringe and at different inj site. Immunosuppressants (eg, irradiation, antimetabolites, alkylating agents, cytotoxic drugs, high-dose corticosteroids): may get suboptimal response.

Twinrix Adverse Reactions

Adverse Reactions

Inj site reactions, headache, fatigue, GI upset, fever.

Twinrix Clinical Trials

Clinical Trials

Immunogenicity: Standard 0-, 1-, and 6-Month Dosing Schedule

In 11 clinical trials, sera from 1,551 healthy adults aged 17–70 years, were assessed following administration of 3 doses of Twinrix on a 0-, 1-, and 6-month schedule. Seroconversion (defined as equal to or greater than assay cut-off depending on assay used: either HAVAB Test [≥20 mIU/mL] or ENZYMUN-Test [≥33 mIU/mL]) for antibodies against HAV was elicited in 99.9% of recipients, and protective antibodies (defined as ≥10 mIU/mL: AUSAB Test) against HBV surface antigen were detected in 98.5% of recipients, 1 month after completion of the 3-dose series.

One of the 11 trials was a comparative trial conducted in a US population given either Twinrix (on a 0-, 1-, and 6-month schedule) or Havrix (0- and 6-month schedule) and Engerix-B (0-, 1-, and 6-month schedule). The monovalent vaccines were given concurrently in opposite arms. An immunogenicity analysis was performed in 533 participants who completed the study according to protocol. Seroconversion rates against HAV and seroprotection rates against HBV were the following:

  • Twinrix (n=264):
    • Month 1:  91.6% (HAV); 17.9% (HBV)
    • Month 2:  97.7% (HAV);  61.2% (HBV)
    • Month 7:  99.6% (95% CI, 97.9-100.0) (HAV); 95.1% (95% CI, 91.7-97.4) (HBV)
  • Havrix and Engerix-B (n=269):
    • Month 1:  98.1% (HAV); 7.5% (HBV)
    • Month 2:  98.9% (HAV); 50.4% (HBV)
    • Month 7:  99.3% (95% CI, 97.3-99.9) (HAV); 92.2% (95% CI, 88.3-95.1) (HBV)
  • The absolute difference in anti-HAV seropositivity rates between groups was 0.36% (90% CI: -1.8, 3.1). Non-inferiority in terms of anti-HAV response was demonstrated (lower limit of the 90% CI was higher than the pre-specified non-inferiority criterion of -4.3%). 
  • The absolute difference in anti-HBsAg seroprotection rates between groups was 2.8% (90% CI: -1.3, 7.7). Non-inferiority in terms of anti-HBV response was demonstrated (lower limit of the 90% CI was higher than the pre-specified non-inferiority criterion of -9.4%).

Since the immune responses to hepatitis A and hepatitis B induced by Twinrix were non-inferior to the monovalent vaccines, efficacy is expected to be similar to the efficacy for each of the monovalent vaccines.

Immunogenicity: Accelerated Dosing Schedule (Day 0, 7, and 21 to 30, Month 12)

In 496 healthy adults, the safety and immunogenicity of Twinrix given on a 0-, 7-, and 21- to 30-day schedule followed by a booster dose at 12 months (n=250), was compared with separate vaccinations with monovalent hepatitis A vaccine (Havrix at 0 and 12 months) and hepatitis B vaccine (Engerix-B at 0, 1, 2, and 12 months) as a control group (n=246).

After a booster dose at Month 12, seroprotection rates for hepatitis B and seroconversion rates for hepatitis A at Month 13 following Twinrix were non-inferior to the control group. Results were the following:

  • Twinrix (n=194-204): 
    • Month 13: 100% (95% CI, 98.1-100.0) (HAV); 96.4% (95% CI, 92.7-98.5) (HBV)
  • Havrix + Engerix-B (n=197-207):
    • Month 13: 100% (95% CI, 98.1-100.0) (HAV); 93.4% (95% CI, 89.0-96.4) (HBV)
  • The absolute difference in anti-HBs seroprotection rates between groups (Havrix + Engerix-B minus Twinrix) was -2.99 (95% CI, -7.80, 1.49). Non-inferiority was demonstrated as the upper limit of the 95% CI was lower than the pre-defined limit of 7%. 
  • The absolute difference in anti-HAV seropositivity rates between groups (Havrix + Engerix-B minus Twinrix) was 0 (95% CI, -1.91, 1.94). Non-inferiority was demonstrated as the upper limit of the 95% CI was lower than the pre-defined limit of 7%. 

Immunogenicity in Adults Older than 40 Years

The effect of age on immune response to Twinrix was studied in 2 trials.

  • The first trial evaluated participants aged 41–63 years (N=72; mean age: 50). All participants were seropositive for anti-HAV antibodies following the third dose of Twinrix. For the hepatitis B response, 94% of participants were seroprotected after the third dose of Twinrix.
  • The second trial included participants aged 19 years and older with a comparison between those older than 40 years (n=183, aged 41–70 years; mean age: 48) and those aged 40 years or younger (n=191; aged 19–40 years; mean age: 33). More than 99% of participants in both age groups achieved a seropositive response for anti-HAV antibodies, and GMTs were comparable between the age groups. In the older adults who received Twinrix, 92.9% (95% CI, 88.2-96.2) achieved seroprotection against hepatitis B compared with 96.9% (95% CI, 93.3-98.8) of the younger adults. The GMT was 1,890 mIU/mL in the older group compared with 2,285 mIU/mL in the younger group.

Duration of Immunity

In two clinical trials, participants (n=129) demonstrated that antibodies to both HAV and HBV surface antigen persisted for at least 4 years after the first vaccine dose in a 3-dose series of Twinrix, given on a 0-, 1-, and 6-month schedule. For comparison, after the recommended immunization regimens for Havrix and Engerix-B, respectively, similar studies of 114 participants have shown that seropositivity to HAV and HBV also persists for at least 4 years.

Twinrix Note

Not Applicable

Twinrix Patient Counseling

Patient Counseling

Advise to report any adverse events to their healthcare provider after adminstration.