Objective: To compare the immunological response of hepatitis B vaccine given by intramuscular injection into the anterolateral thigh and ventrogluteal site of infants up to 10 months old at initiation of vaccination.
Methods: An open, randomized study of 200 healthy infants recruited from a single practice in a small regional town in New South Wales was carried out. Infants were vaccinated with hepatitis B vaccine (Engerix-B 10 µg) using a 0 months, 1 month, 6 months regimen, with venous blood being collected from children 4−6 weeks after the last dose of vaccine for quantitative determination of hepatitis B surface antibody (anti-HBs) titre. Infants with anti-HBs titre ≥ 100mIU/mL were considered to be ‘good’ responders and were unlikely to acquire clinically significant hepatitis B infection. Infants with anti-HBs titre < 100mIU/mL were considered to be ‘poor’ responders and were given a booster dose of Engerix-B 20 µg; serology was repeated for anti-HBs titre 2−3 months after this injection.
Results: Quantitative anti-HBs titre was obtained from 177 infants: 171 4−6 weeks after the last dose of vaccine; 87 at the ventrogluteal site (46 boys, 41 girls); and 84 at the anterolateral thigh site (38 boys, 46 girls). Good antibody response (anti-HBs titre ≥ 100mIU/mL) was not significantly different for the two sites (ventrogluteal 96.6%, anterolateral thigh 93.2%), and antibody geometric mean titres (GMT) for anti-HBs were comparable for the two sites (ventrogluteal 2071.2 ± 5.8mIU/mL, anterolateral thigh 2073.2 ± 5.2mIU/mL).
Conclusion: The ventrogluteal and anterolateral thigh vaccination sites in infants are immunologically comparable for hepatitis B vaccine. Presumably the variance of this study with studies of adults reflected the uniform injection of vaccine antigen into muscle tissue in infants.