Side-by-side Comparative Study of the Immunogenicity of the Intramuscular and Intradermal Rabies Post-exposure Prophylaxis Regimens in a Cohort of Suspected Rabies Virus Exposed Individuals.

All World Health Organization (WHO) pre-qualified rabies vaccines for humans are inactivated tissue culture rabies virus formulations produced for intramuscular (IM) administration. Due to costs and vaccine shortage, dose-saving intradermal (ID) administration of rabies post-exposure prophylaxis (PEP) is encouraged by WHO. This study compared the immunogenicity of the ID 2-site, 3-visit Institut Pasteur Cambodge (IPC) PEP regimen to the IM 1-site, 4-visit 4-dose Essen regimen using Verorab vaccine (Sanofi). The development of neutralizing antibodies (nAbs) and T cell response was assessed in 210 patients with a category II or III animal exposure in a rabies-endemic country. At day 28, all participants developed nAbs (≥0.5 IU/mL), irrespective of PEP scheme, age, or administration of rabies immunoglobulin. T cell response and nAb titers were similar for both PEP schemes. This study demonstrated that the 1-week ID IPC regimen is as effective as the 2-week IM 4-dose Essen regimen in inducing an anti-rabies immune response under real-life PEP.

One-week intramuscular or intradermal pre-exposure prophylaxis with human diploid cell vaccine or Vero cell rabies vaccine, followed by simulated post-exposure prophylaxis at one year: A phase III, open-label, randomized, controlled trial to assess immunogenicity and safety.

Shorter rabies pre-exposure prophylaxis (PrEP) regimens may offer improved convenience and feasibility over classic 3-week regimens, for example in regions with poor access to vaccines or for travelers to rabies-endemic regions. In this multicenter, open-label, controlled trial, 570 healthy participants aged 2-64 years were randomized to receive: 1-week PrEP (vaccination days [D]0 and 7; Group 1) or classic 3-week PrEP regimen (D0, D7, and D21; Group 2) with one 1.0 mL intramuscular [IM] dose of human diploid cell culture rabies vaccine (HDCV) at each visit; 1-week PrEP with two 0.1 mL intradermal (ID) HDCV doses at each visit (Group 3); or 1-week PrEP with one 0.5 mL IM dose (Group 4) or two 0.1 mL ID doses (Group 5) of Vero cell rabies vaccine (PVRV) at each visit. Participants received simulated post-exposure prophylactic (PEP) vaccination (two IM or ID doses of HDCV or PVRV three days apart) one year later. Rabies virus neutralizing antibody titers and seroconversion (titers ≥ 0.5 IU/mL) rates were assessed 14 days and up to 1 year post-PrEP, and pre- and post-PEP. Safety was assessed throughout the study. Seroconversion rates were high 14 days post-last PrEP injection (ranging from 96.7 % to 97.2 % across groups 1, 3-5; 1-week PrEP) and reached 100 % in Group 2 (3-week PrEP). Non-inferiority of Group 1 versus Group 2 in terms of seroconversion rates 14 days post-last PrEP injection (primary objective) was not demonstrated. After simulated PEP, all groups showed rapid and robust immune responses, with all but one participant achieving seroconversion (titers ≥ 0.5 IU/mL). There were no safety concerns, and the tolerability profiles of the vaccines were similar across the groups. A 1-week, IM or ID PrEP regimen with HDCV or PVRV provided efficacious priming, enabling rapid robust anamnestic responses to simulated PEP 1 year later across age groups. ClinicalTrials.gov number: NCT03700242. WHO Universal Trial Number (UTN): U1111-1183-5743.