Ask the Experts: Combination Vaccines: HepA-HepB (Twinrix, GSK)

Results (6)

Twinrix is an inactivated combination vaccine containing both hepatitis A virus (HAV) and HBV antigens. The vaccine contains 720 EL.U. of hepatitis A antigen (half of the Havrix adult dose) and 20µg of hepatitis B antigen (the full Engerix-B adult dose). In the U.S., Twinrix is licensed for use in people who are age 18 years or older. It can be administered to people who are at risk for both hepatitis A and hepatitis B, such as certain international travelers, people with chronic liver disease, men who have sex with men, illegal drug users, or to people who simply want to be immune to both diseases. A Twinrix series consists of 3 doses given intramuscularly on a 0, 1, and 6 month schedule.

Last reviewed: July 15, 2023

Minimum intervals for Twinrix are 4 weeks between dose #1 and dose #2, and 5 months between dose #2 and dose #3.

Last reviewed: July 15, 2023

Yes. This was a vaccine administration error since Twinrix, a combination hepatitis A/hepatitis B vaccine, is not licensed for people younger than 18. However, the hepatitis A and hepatitis B components can be counted as valid doses. The third dose of the Twinrix series should be given at least five months after the second dose.

Last reviewed: July 15, 2023

Twinrix is normally given as a 3-dose series on a schedule of 0, 1, and 6 months. However, if someone needs protection sooner (e.g., imminent foreign travel), you can give it as a 4-dose series at intervals of 0, 7, and 21–30 days, followed by a fourth (booster) dose at least 12 months after the first dose.

Last reviewed: July 15, 2023

Twinrix is licensed as a 3-dose series for people age 18 years and older. If Twinrix is not available or if you choose not to use Twinrix to complete the hepatitis A (HepA) and hepatitis B (HepB) series, you should do the following:

  • If 1 dose of Twinrix was given, complete the series with 2 adult doses of HepA and 2 adult doses of HepB.
  • If 2 doses of Twinrix were given, complete the schedule with 1 adult dose of HepA and 1 adult dose of HepB.

Another way to consider this is as follows:

  • A dose of Twinrix contains a standard adult dose of HepB and a pediatric dose of HepA. So, a dose of Twinrix can be substituted for any dose of the HepB series but not for any dose of the HepA series.
  • Any combination of 3 doses of adult HepB or 3 doses of Twinrix is a complete series of HepB vaccine
  • One dose of Twinrix and 2 doses of adult HepA is a complete series of HepA
  • Two doses of Twinrix and 1 dose of adult HepA is a complete series of HepA
Last reviewed: July 21, 2023

No. Twinrix contains 50% less hepatitis A antigen component than Havrix, GSK’s monovalent HepA vaccine [720 vs. 1440 EL.U.], so the patient would not receive the recommended dose of HepA vaccine antigen.

Last reviewed: July 15, 2023

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