A comparative immunogenicity and safety trial of two different schedules of single-visit intradermal rabies post-exposure vaccination following a single-visit pre-exposure vaccination [Epub ahead of print]

Abstract

BACKGROUND: Effective and safe single-visit rabies vaccination for pre- and post-exposure prophylaxis (PrEP and PEP) could substantially simplify rabies prevention and therefore increase compliance. METHODS: In a comparative trial, 303 healthy adults received a primary vaccination consisting of two intradermal (ID) doses of 0.1mL of the purified chicken embryo cell vaccine (PCEV) during a single visit. One year later, subjects were randomly assigned to receive either four or two ID PEP booster doses of 0.1mL of PCEV during a single visit. The primary endpoint for immunogenicity was the percentage of subjects with an adequate antibody level (>0.5 IU/mL) seven days after the booster doses. The safety endpoint was the proportion of participants developing adverse events (AE) following primary and/or booster vaccination. RESULTS: ll subjects, except one (99.3%) in each study group, had a rabies antibody titer >0.5 IU/mL on day 7 following the booster schedules. Subjects exposed to the four-dose PEP schedule had a geometric mean titer of 20 IU/mL versus 14 IU/mL for the two-dose PEP schedule (p=0.0228). Local reactions at the injection site following PrEP and PEP were mild and transient and only seen in 14.9% and 49.6 to 53% of the participants respectively. No serious AE were reported. CONCLUSION: In healthy adults, a two-dose (2x 0.1mL) single-visit intradermal post-exposure prophylaxis schedule was as immunologically adequate and safe as a four-dose (4x 0.1mL) single-visit PEP schedule, seven to twenty-eight months following a two-dose (2x 0.1mL) single-visit intradermal pre-exposure prophylaxis.