• Tereza Monteiro Ribeiro and Raymundo Soares Azevedo.
• Basic Health Unit of Campo dos Alemães, São José dos Campos, SP, Brazil.
• Clinics (Sao Paulo). 2006 Oct 1; 61 (5): 387394387-94.

PurposeTo detect seroconversion of hepatitis B vaccine and antibody waning 3 years after vaccination in children immunized according to the World Health Organization schedule and its relationship to the mother's serostatus during pregnancy.MethodsA serological study was carried out in São José dos Campos. Blood samples from pregnant women were taken for hepatitis B marker serology. To evaluate seroconversion in infants born to these women, serology was performed 1 month after they were vaccinated with recombinant vaccine. Another group of children was evaluated 3 years after being immunized.ResultsAmong 224 pregnant women, 0.9% were positive for hepatitis B surface antigen, 8.0% for antibodies to the surface antigen, and 4.5% for antibodies to the virus core. Seroconversion among 174 infants was as follows: absent in 18 children (10.35%), low level in 15 (8.62%), intermediate level in 26 (14.94%), and a high level (good response) in 115 (66.09%). Antibody positivity after 3 years was as follows: absent in 8 children (7.92%), low level in 51 (50.5%), intermediate level in 20 (19.8%), and high level in 22 (21.78%). Considering the age that the vaccine was administered, a significant proportion of non-seroconverters was found among children who had received the complete 3-dose schedule before 9 months (P = 0.023). Another factor that significantly contributed to the lack of seroconversion was the presence of any serological marker for hepatitis B during pregnancy (P = 0.044).ConclusionsData gathered in this work show that the immunization schedule for hepatitis B in low or moderate prevalence areas should be revised in order to optimize seroconversion.

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