Response to hepatitis B vaccine differs by birthweight among neonates

Objectives: To assess the immunogenicity of same needle length of hepatitis B vaccine for infants with different birthweights. Previous studies have focused on obese adolescents and adults that have lower titers of antibody response to hepatitis B vaccine. The aim of this study was to compare antibody titers of macrosomic and other neonates for hepatitis B antibody with the same needle length.

Methods: 96 healthy infants were vaccinated at birth, 1, and 6 months of age with hepatitis B vaccine, with follow-up to 7 months of age. Cord blood and seventh month hepatitis B antibody titer were repeated. Infants were divided into three groups, according to their birthweight, as macrosomic, appropriate for gestational age and small for gestational age. The same needle with 26 G and 16 mm length was used for all infants.

Results: Macrosomic infants with a birthweight over 4000 g had lower antibody levels than small and appropriate for gestational age infants.

Conclusions: These data support the hypothesis that birthweight has an effect on response to HBV vaccine. Using the same needle length for immunization of macrosomic infants for hepatitis B reveals significantly reduced antibody titers, this can be related also to possible endogenous factors. Further studies are needed to assess appropriate needle length and effects of other factors on vaccine reactogenicity for macrosomic infants.