A randomized non-inferiority clinical study to assess post-exposure prophylaxis by a new purified vero cell rabies vaccine (Rabivax-S) administered by intramuscular and intradermal routes.

BACKGROUND: Rabies is a 100% fatal disease but preventable with vaccines and immunoglobulins. We have developed a new purified vero cell rabies vaccine (Rabivax-S) and evaluated its safety and immunogenicity in post-exposure prophylaxis by intramuscular (IM) and intradermal (ID) routes. METHODS: This was a randomized active-controlled non-inferiority study in 180 individuals (age 5years and above) with suspected rabies exposure (90 each with WHO Category II and Category III exposures). The participants received either Rabivax-S (1mL IM; five doses), Rabivax-S (0.1mL ID; eight doses) or purified chick embryo cell vaccine (PCEC, Rabipur®) (1mL IM; five doses). The IM doses were given on Day 0, 3, 7, 14 and 28 while the ID doses were given on days 0, 3, 7 and 28. Category III patients also received a human rabies immunoglobulin (HRIG) on Day 0. Adverse events (AEs) were recorded with diary cards till day 42. Rabies neutralizing antibody levels were measured on day 0, 7, 14, 28 and 42. RESULTS: In both the category II and III patients, the geometric mean concentration (GMC) ratios of Rabivax-S IM and Rabivax-S ID groups to PCEC IM were more than 1, thus proving the non-inferiority. GMCs were similar or higher in Rabivax-S groups at all the time points. Seroresponse against rabies (RFFIT titre⩾0.5IU/mL) was achieved in all participants. Mostly mild local and systemic adverse events were reported across the three groups and all resolved without sequelae. CONCLUSIONS: Rabivax-S was well tolerated and showed immunogenicity comparable to a licensed rabies vaccine by both IM and ID routes in post-exposure prophylaxis. Registry No.: CTRI/2012/11/003135.

Safety and immunogenicity of a new purified vero cell rabies vaccine (PVRV) administered by intramuscular and intradermal routes in healthy volunteers.

BACKGROUND: Rabies is 100% fatal but preventable with modern vaccines and immunoglobulins. There is a huge demand for rabies vaccines in developing countries of Asia and Africa. We have developed a new purified vero cell rabies vaccine (PVRV) and evaluated its safety and immunogenicity in healthy volunteers by intramuscular (IM) and intradermal (ID) routes of vaccination. METHODOLOGY: Sixty adults aged between 18 and 50 years were recruited in this actively controlled Phase I clinical study and were randomized to receive three 1 ml or 0.1 ml doses of new PVRV intramuscularly or intradermally on days 0, 7 and 21. The control group received commercially available PVRV (Verorab) by intramuscular route. Adverse events (AEs) were recorded with diary cards till day 28 post-vaccination. Immunogenicity was assessed on day 0, 7, 21 and 42 by rapid fluorescence focus inhibition test (RFFIT). RESULTS: In all, 116 solicited local and systemic events were reported across the three groups. Most were mild and resolved without sequelae. Also the few unsolicited events, deemed unrelated to the study vaccines, caused no problems. No significant changes in the routine laboratory parameters were found. Two doses of a vaccine elicited protective titres (≥ 0.5 IU/ml) in all subjects, the GMTs varying between 0.57 and 0.69 IU/ml on day 7, 3.07 and 3.97 IU/ml on day 21, and 6.12 and 8.52 IU/ml on day 42 post-vaccination. CONCLUSIONS: PVRV was well tolerated and showed good immunogenicity regardless of whether administered intramuscularly or, using a tenth of that volume, intradermally. Further studies with this new vaccine are warranted.