A randomized, multicenter, open-label clinical trial to assess the anamnestic immune response 4 to 8 years after a primary hepatitis B vaccination series.

This open-label, randomized study challenged 4- to 8-year-old children from Spain (N = 1478) with a single dose of hepatitis B vaccine to estimate anamnestic responses. At the time of preimmunization, 15.9% to 51.2% of subjects had antibody values ≥10 mIU/mL. One month postimmunization, 91.6% to 97.3% of subjects had antibody titers ≥10 mIU/mL. There were no serious, vaccine-related, adverse experiences, and no discontinuations as a result of adverse experience.