Evaluation of rabies immunogenicity and tolerability following a purified chick embryo cell rabies vaccine administered concomitantly with a Japanese encephalitis vaccine.

Summary Background For individuals traveling at short notice to rabies and Japanese encephalitis (JE) endemic countries, concomitant administration of travel vaccines within a short period is often required. Methods The aim of this study was to determine whether an accelerated (one-week: Days 1–8) pre-exposure rabies (Rabipur ® , Novartis Vaccines) vaccination regimen administered concomitantly with a Japanese encephalitis (JE) vaccination (Ixiaro ® , Valneva) regimen, is non-inferior to the standard (four-week: Days 1, 8, 29) rabies regimen administered alone or concomitantly with the JE vaccine. Healthy adults (18 to ≤65 years) were randomized into Rabies + JE-Standard, Rabies + JE-Accelerated, Rabies-Standard and JE-Standard groups. Relative immunogenicity for rabies in each regimen was assessed using the rapid fluorescent focus inhibition test. Safety was evaluated up to and including Day 57. Results Non-inferior immunogenicity for rabies was established between the Rabies + JE-Accelerated group compared to both the Rabies-Standard and Rabies + JE-Standard groups; as well as between the Rabies + JE-Standard regimen and the Rabies-Standard regimen. By Day 57, adequate neutralizing levels were achieved by 97–100% of subjects across all groups. Adverse events (AEs) were comparable for all groups. Conclusions An accelerated pre-exposure rabies and JE vaccination regimen is non-inferior to the standard four-week rabies regimen and may thus provide a more convenient regimen for individuals traveling to endemic countries at short notice. NCT01662440 .