COMPARISON STUDY OF THE IMMUNOGENICITY AND SAFETY OF 5-MU-G AND 10-MU-G DOSAGES OF A RECOMBINANT HEPATITIS-B VACCINE IN HEALTHY-CHILDREN

Objective, To compare the immunogenicity and safety of 5 mu g with 10 mu g of Engerix-B(R) recombinant hepatitis B vaccine when given to hea lthy children, 2 to 6 years of age, Methods. Randomized multicenter st udy of seronegative children 2 to 6 years of age who received Engerix- B(R) hepatitis B vaccine either 5 mu g/0.25 ml or 10 mu g/0.5 ml (the current Food and Drug Administration-approved dosage of Engerix-B(R) i n children) at 0, 1 and 6 months. Serum was obtained at 1, 3, 6 and 8 months after the first vaccine dose was given for antibody measurement , Results, A total of 223 subjects mere screened and received the firs t dose of vaccine. Of these subjects 193 continued in the study, Both dosages proved to be highly immunogenic, producing high seroconversion and seroprotection rates and geometric mean antibody to hepatitis B s urface antigen concentrations after 3 doses, The geometric mean concen trations of seroconverters at Months 6 and 8 were significantly greate r for the 10-mu g group compared with the 5-mu g group, Both dosages w ere well-tolerated and no serious adverse events were reported, Conclu sions. There was a significant reduction in geometric mean concentrati ons on lowering the dosage of Engerix-B(R) from 10 to 5 mu g in childr en 2 to 6 years of age. Although a high seroprotection rate was elicit ed by the 5-mu g dose, the lower antibody concentrations achieved may make this lower dosage less desirable in the long term, Further studie s are required to examine the need for booster doses of vaccine with b oth dosing schedules.