Requirement of a Booster Dose of Hepatitis B Vaccine in Children With Thalassemia After 5 Years of Primary Vaccination: A Prospective Study.

OBJECTIVE

To determine anti-HBs antibody levels in multi-transfused children with beta-thalassemia major who had received primary hepatitis B vaccination ≥5 years ago, and to document their antibody response to a booster dose of hepatitis B vaccine.

METHODS

We included 85 children each of beta-thalassemia major and age-matched healthy controls, who had completed primary hepatitis B vaccination ≥5 years ago. Participants were assessed for anti-HBs titres, and those with beta-thalassemia major who were seronegative (titres<10 mIU/mL) were administered a single booster dose of hepatitis B vaccine. CD4 counts, serum levels of IL-2 and IFN-g, and anti-HBs titres were evaluated at baseline and following booster dose of vaccine.

RESULTS

Seroprotection rates for hepatitis B after an average (SD) duration of 10.8 (3.8) years of completion of primary immunization were significantly higher among children with beta thalassemia major compared to healthy controls (72.9% vs. 52.9%, P=0.007). All the 23 seronegative children with beta-thalassemia major achieved seroprotection after a single booster dose of hepatitis B vaccine.

CONCLUSIONS

A single booster dose of hepatitis B vaccine after 5 years of primary immunization is adequate to provide seroprotection to multi-transfused children with beta-thalassemia major.