Rapidity and magnitude of antibody response to duck-embryo rabies vaccine administered as a pre-exposure regimen.

Rabies virus appears in the central nervous system within hours after it is introduced peripherally. It has been suggested that rapidity of appearance is an important factor in providing immunity against rabies. Since pre-exposure vaccination of man against this disease is performed in high-risk occupational groups, it is important to know the time-interval between administration of vaccine and appearance of antibody. This report shows that persons who received a booster inoculation of duck-embryo rabies vaccine 6 months after a pre-exposure course of 3 sensitizing intradermal doses of the same vaccine responded rapidly with the production of demonstrable antibody. That response was not assured if the person had failed to develop demonstrable antibody after the primary series. Antibody response to the booster occurred 3-8 days earlier than the appearance of antibody in persons who, in earlier studies, had received an intensive primary course of 14-21 subcutaneous doses of vaccine.The authors suggest that all persons who have received a primary course of rabies immunization should be tested for rabies antibody to determine whether the antibody-forming mechanism has been properly conditioned to respond to a booster injection in the event of subsequent exposure to rabies virus.