Long-term anti-rabies antibody persistence following intramuscular or low-dose intradermal vaccination of young Vietnamese children

Vietnamese children received purified Vero cell rabies vaccine 1 year after a primary series (Y0) and again 5 years later (Y5), either as intramuscular or 1/5th dose intradermal injections concomitant with diphtheria, tetanus, pertussis and oral poliomyelitis vaccines. Antibody levels were assayed annually for 5 years. All subjects in both groups had anti-rabies antibody titres considered protective after the Y0 booster. Rabies seroprotection rates and geometric mean titres gradually decreased similarly in both groups. Seroprotection after the Y5 booster was 100% in both groups. Satisfactory immunogenicity, long-term antibody persistence and an anamnestic response were conferred by both routes, greatly simplifying any future post-exposure prophylaxis.