Introduction:
Modern anti cancer therapy causes an immunosuppressive state that renders the patient susceptible to infection by bacteria, fungi, virus and protozoa. Hepatitis B virus (HBV) infection is one such infection which is common in children on chemotherapy. Control of disease and carrier state can be achieved through effective vaccination. The immunogenic response however may be impaired due to prolonged immunosuppressive therapy.
Aims and objectives:
- To study the immunogenicity of Hepatitis B virus vaccine in children on intensive chemotherapy.
- To determine the optimal dose, schedule and timing to get the best seroconversion rates.
Methodology:
This prospective study was conducted at Christian Medical College & Hospital, Vellore, between March 2003 and August 2004. Children newly diagnosed with lymphoid malignancy and solid tumors requiring intensive chemotherapy were screened for Hepatitis B infection. Those with negative serology formed the study group. They were divided into two groups in which "A" were given conventional dose of Hepatitis B Vaccine while "B" received double the dose. Antibody titers were checked one month after the 3rd dose. A booster dose was given to those with low antibody titer.
Results:
68 children from various states of India were screened. 33 children with positive anti HBs antibody level due to prior immunization and one with positive Hepatitis B core IgM were excluded. Of the remaining 34 children, 3 did not give their consent. Thus 31 children were recruited either in Group A or Group B. 10 children in Group A and 11 in Group B completed the study.
In Group A, the seroconversion was 10% (1/11) and in Group B 36% (4/11) after the 3rd dose of vaccine. Five each of the non responders in groups A and B were given a booster dose. None of them in group A and only one in group B seroconverted (with overall seroconversion increasing to 45.5% in B). The difference in seroconversion response with the booster dose was statistically significant. (p=0.0362) at error level 10%.
In addition, the initially screened seropositive patients showed a significant fall in the previously acquired antibody titer level after chemotherapy.
Conclusion:
- Children on cancer chemotherapy need to be screened for hepatitis B virus markers at initiation of chemotherapy and should be appropriately vaccinated if found to have no protective antibody.
- Conventional dose of hepatitis B vaccine is not effective during intensive phase of chemotherapy. All unimmunised children on treatment need to be given double dose of vaccine.
- Due to fall in the acquired antibody level after chemotherapy revaccination is advised in those with previous immunization.
