I have seen adults who have had 1 or 2 doses of Twinrix (HepA-HepB), but we only carry single-antigen vaccine in our practice. How should we complete their vaccination series with single-antigen vaccines?

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