Twinrix® is indicated for use in persons 18 years of age or older who are at risk for both hepatitis A and hepatitis B. It is given as a three-dose series at birth, one month, and six months of age and is administered intramuscularly. The first and third doses of Twinrix® should be separated by at least six months. The first and second doses should be separated by at least four weeks, and the second and third doses should be separated by at least five months.