Persistence of antibodies in children after intradermal or intramuscular administration of preexposure Primary and booster immunizations with purified Vero cell rabies vaccine

Background. The use of intradermal lid) injections of purified Vero cell rabies vaccine (PVRV) for preexposure prophylaxis has not been well-established. We studied the safety and immunogenicity of id and intramuscular (im) PVRV injections for primary and booster preexposure immunizations. Methods. One of two rabies preexposure PVRV regimens comprising three doses of either 0.1 mi id or 0.5 mi im administered during 28 days was assigned at random to 190 school children. One booster dose was given 1 year later either id or im, according to their initial randomization group. Serologic results were available from 155 (82%) children at 1 year after primary immunization and 118 (62%) children at 2 years after booster. Results. Although children vaccinated id had significantly lower rabies-neutralizing antibody titers after primary immunization as well as after booster than children vaccinated im (P < 0.001 for all time points), there were no significant differences in the percentages of children with adequate titers (greater than or equal to 0.15 IU/ml) between the id and im groups after both primary and booster immunizations. Mild local reactions were more frequent after id vaccination. Mild or moderate systemic reactions were infrequent and similar after id and im vaccinations. Fever and headache were reported by less than or equal to 6%. The reactions after booster were not different from those of postprimary immunization. Conclusions. Purified Vero cell rabies vaccine appears to be safe and immunogenic for primary and booster preexposure immunizations. An id PVRV preexposure regimen should be useful especially for rabies-endemic countries with low per capita income.