 In the United States, Twinrix is approved by the Food and Drug Administration (FDA) for those aged 18 and older.In some countries outside the United States, notably Canada and Europe, Twinrix is known as Twinrix Adult or Ambirix and a pediatric formulation, called Twinrix Junior or Twinrix Paediatric, is available.Routine Twinrix vaccination is administered by intramuscular injection in the deltoid area using a schedule of three separate doses at 0, 1, and 6 months ([minimum intervals