RISK-FACTORS FOR SYSTEMIC HYPERSENSITIVITY REACTIONS AFTER BOOSTER VACCINATIONS WITH HUMAN-DIPLOID CELL RABIES VACCINE - A NATIONWIDE PROSPECTIVE-STUDY

To determine the incidence of and risk factors for adverse reactions f ollowing the boosters, we conducted a nationwide prospective study of persons receiving pre-exposure booster vaccination with human diploid cell rabies vaccine (HDCV). Persons who had previously received three pre-exposure doses of HDCV and whose rabies neutralizing antibody titr es were less-than-or-equal-to 1: 5 were enrolled in the study if they stated that they intended to receive a booster. Of the 98 persons enro lled in the study, 40 (41%) were in risk groups for whom boosters are not recommended. Three (3%) of 98 developed generalized urticaria or w heezing within 1 day of receiving boosters and three others (3%) devel oped urticaria 6 to 14 days after the booster. No differences were fou nd between individuals with reactions (either type) and those with no adverse reaction according to age, gender, occupation, history of prev ious allergies, or time since or route of primary vaccination. Reactio ns were somewhat more common among persons who received primary vaccin ations by the intramuscular route (i.m.) and booster vaccinations by t he intradermal route (i.d.) (3/15, 20%) or primary vaccinations i.d. a nd booster vaccinations i.m. (2/10, 20%), and somewhat less common amo ng persons who received both these vaccinations i.d. (1/52, 2%) or i.m . (0/7). The number of persons who develop allergic reactions may be m inimized by administering vaccinations only when vaccination is strict ly indicated. The influence of the route of primary and booster vaccin ations on the development of reactions deserves further study.