Protecting Indian schoolchildren against rabies: pre-exposure vaccination with purified chick embryo cell vaccine (PCECV) or purified verocell rabies vaccine (PVRV)

Abstract

Although rabies can be effectively prevented by means of preexposure or post-exposure prophylaxis, in India, an estimated 17,000 to 20,000 human rabies deaths occur annually. Tragically, 50% of these victims are children under the age of 15. In addition to immediate post-exposure prophylaxis measures, including active and passive immunization, pre-exposure vaccination using tissue culture vaccines is a safe and effective but highly underutilized method of preventing rabies in humans living or working in areas at risk. This study assessed the safety and immunogenicity of Purified Chick Embryo Cell Vaccine (PCECV) and Purified Verocell Rabies Vaccine (PVRV), administered as a three-dose intramuscular pre-exposure regimen on days 0, 7 and 28 in 175 healthy schoolchildren. PCECV was administered after reconstitution using either 1.0 mL or 0.5 mL (half the diluent volume) and PVRV was given after reconstitution with 0.5 mL. Vaccine safety was assessed observer-blind, including pain assessment with a validated visual analogue scale for children. Rabies virus neutralizing antibody (RVNA) concentrations were measured on day 49 by RFFIT. All children developed adequate RVNA concentrations above 0.5 IU/mL. Solicited local and systemic reactions were within the range expected, pain after vaccination was reported in 2 to 12% of study subjects, fever was reported in 2 to 5%. There was no statistical difference by vaccination group or vaccination day. No unexpected or serious adverse event was reported during the study. In conclusion, PCECV and PVRV are safe and immunogenic when administered intramuscularly for pre-exposure prophylaxis of rabies in children. A 1.0 mL dilution volume for PCECV was as well tolerated as PVRV or PCECV reconstituted in half the volume.