Immunogenicity of Two Versus Three Doses of Hepatitis B Vaccine When Administered to Children Aged 2-18 Months: A Randomized Clinical Trial.
BACKGROUND: A 2-dose hepatitis B vaccination schedule is highly immunogenic in children aged ≥1 year, but data for infants are scarce. Our goal was to compare the immunogenicity of 2- and 3-dose hepatitis B vaccination schedules in this population. METHODS: Children in the experimental group were recruited at 2 months of age and randomized to receive a homologous (Infanrix-hexa/Infanrix-hexa) or heterologous (Infanrix-hexa/Twinrix) 2-dose schedule at 2 and 12 months. Children in the control group were recruited at 18 months and had received a homologous 3-dose schedule (Infanrix-hexa/Infanrix-hexa/Infanrix-hexa) at 2, 4, and 18 months. All groups received a challenge dose (Twinrix) 3 years later. RESULTS: One month after the primary series, seroprotection rates (anti-HBs ≥10 mIU/mL) were high and similar among the 3 groups (heterologous 2-dose, 91.7%; homologous 2-dose, 90.9%; 3-dose, 94.2%). Geometric mean titers (GMTs) were lower in the 2-dose groups than in the 3-dose group. Post-challenge dose, the majority exhibited an anamnestic response, similar across all 3 groups (heterologous 2-dose, 97.2%; homologous 2-dose, 95.5%; 3-dose, 92.7%). GMTs were numerically higher in the heterologous 2-dose group (9380.5 mIU/mL) than in the 3-dose group (6900.6 mIU/mL) (P = .4). The proportion exhibiting local reactions was significantly lower after the heterologous 2-dose schedule than after the homologous 2-dose schedule. CONCLUSIONS: The anamnestic response 3 years after 2-dose (2 and 12 months) and 3-dose (2, 4, and 18 months) hepatitis B vaccination schedules was similar. The heterologous 2-dose schedule was more immunogenic and less reactogenic than the homologous 2-dose schedule.