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Long-term Immunogenicity of Hepatitis B Vaccination in children
Abstract
Background: Chronic hepatitis B is a major global healthcare problem. Immunization is the most effective way to prevent transmission of hepatitis B virus (HBV) and, hence, the development of acute and chronic hepatitis B. Sero-protection after vaccination, defined as anti hepatitis B surface antibody
(anti-HBS) ≥ 10mIU/mL, is achieved in over 95% of all vaccinated children. Objective: The aim of the work is to detect the long-term immunogenicity of the vaccine in children
after five and ten years of vaccination, also to test for anamnestic reaction to determine whether or not a booster dose is needed. Methods: This study included 200 healthy children. Before being included in the study children were screened for the presence of HBV infection. The children were divided into two groups according to age (each group contains 100 children). Their data are included. Group `A` included 53 males and 47 females, around 6 years old, all children were vaccinated 5 years ago. Group `B` included 27 males and 73 females, around 11 years old. All children vaccinated 10years ago. HBsAb titre was tested in their blood, booster dose of the vaccine was given to children whose HBsAb was < 10 mIU/ml, then one and half months later, another blood sample from each of them was retested for HBsAb to evaluate the response to this booster dose of vaccine. Results: when testing the serum of the children in both groups (A&B) for HBsAb and its titre, both groups have a wide range concerning the level of HBsAb (2→1000) mlU/ml). Our data proves the decline of antibodies titre with time, and there was significant difference between the two groups in the level of HBsAb . There was no significant difference in anti-HBs between girls and boys in group A in contrary to group B. In group A, from the nineteen children who needed a booster vaccination dose, 14 were vaccinated. Serum sample was taken from 10 children after one and half month from vaccination, out of these 10, 9 (90%) responded by increased level of HBs antibodies and only one child did not respond, Six (66.6%) of the nine showed an adequate response. In group B, fifty two children in this group had antibody titre < 10, forty eight were vaccinated. After one and half month, 34 children were tested again for HBsAb. Two out of the thirty four children did not respond (5.8%) and 32 (94.2%) responded by an increase in the antibody titre. Of those responded, 19 had adequate response (HBsAb ≥ 100) and 13 had hypo-response (HBsAb lies between 10-100). Therefore, 80% of the boys who were retested for HBsAb after vaccination responded adequately while 51.7% of the corresponding girls responded adequately. There was no significant difference in antibodies titre responding to the testing dose with p value =0.814. Conclusion: Hepatitis B vaccine is an effective and successful way for preventing HBV infection. There is persistence of protective antibodies after primary vaccination in most of children with decline of the levels over time. Even so, no need for booster dose at least for 10 years after vaccination.
Key words: HBV, HB Vaccination, child immunity
(anti-HBS) ≥ 10mIU/mL, is achieved in over 95% of all vaccinated children. Objective: The aim of the work is to detect the long-term immunogenicity of the vaccine in children
after five and ten years of vaccination, also to test for anamnestic reaction to determine whether or not a booster dose is needed. Methods: This study included 200 healthy children. Before being included in the study children were screened for the presence of HBV infection. The children were divided into two groups according to age (each group contains 100 children). Their data are included. Group `A` included 53 males and 47 females, around 6 years old, all children were vaccinated 5 years ago. Group `B` included 27 males and 73 females, around 11 years old. All children vaccinated 10years ago. HBsAb titre was tested in their blood, booster dose of the vaccine was given to children whose HBsAb was < 10 mIU/ml, then one and half months later, another blood sample from each of them was retested for HBsAb to evaluate the response to this booster dose of vaccine. Results: when testing the serum of the children in both groups (A&B) for HBsAb and its titre, both groups have a wide range concerning the level of HBsAb (2→1000) mlU/ml). Our data proves the decline of antibodies titre with time, and there was significant difference between the two groups in the level of HBsAb . There was no significant difference in anti-HBs between girls and boys in group A in contrary to group B. In group A, from the nineteen children who needed a booster vaccination dose, 14 were vaccinated. Serum sample was taken from 10 children after one and half month from vaccination, out of these 10, 9 (90%) responded by increased level of HBs antibodies and only one child did not respond, Six (66.6%) of the nine showed an adequate response. In group B, fifty two children in this group had antibody titre < 10, forty eight were vaccinated. After one and half month, 34 children were tested again for HBsAb. Two out of the thirty four children did not respond (5.8%) and 32 (94.2%) responded by an increase in the antibody titre. Of those responded, 19 had adequate response (HBsAb ≥ 100) and 13 had hypo-response (HBsAb lies between 10-100). Therefore, 80% of the boys who were retested for HBsAb after vaccination responded adequately while 51.7% of the corresponding girls responded adequately. There was no significant difference in antibodies titre responding to the testing dose with p value =0.814. Conclusion: Hepatitis B vaccine is an effective and successful way for preventing HBV infection. There is persistence of protective antibodies after primary vaccination in most of children with decline of the levels over time. Even so, no need for booster dose at least for 10 years after vaccination.
Key words: HBV, HB Vaccination, child immunity
