Safety and Immunogenicity of purified chick embryo cell rabies vaccine (VaxiRab N) administered intradermally as post exposure prophylaxis.

The affordability to rabies vaccine for intramuscular administration in post exposure prophylaxis is a major constraint. Therefore, in countries, where there are financial constraints, World Health Organization recommends intradermal rabies vaccination that reduces the quantity and cost of vaccination. This study was done to evaluate the safety and immunogenicity of indigenously developed rabies vaccine (VaxiRab N) in comparison to a WHO recommended rabies vaccine (Rabipur) with demonstrated efficacy when administered by intradermal route using updated Thai Red Cross regimen. Eighty-six dog bite cases were randomly given either VaxiRab N (n = 43) or Rabipur (n = 43) as post exposure prophylaxis. The rabies virus neutralizing antibody concentrations on days 14, 28, 90, and 180 were tested by modified rapid fluorescent focus inhibition test. The geometric mean RVNA concentration of both the groups were compared using t- test and was found that, P value > 0.05 on all days, thus showing no significant difference between the 2 groups. The adverse drug events were also compared using Z-test and was found to be not statistically significant (Z = 1.476, P = 0.139). In conclusion, VaxiRab N was found to be safe and effective in post exposure prophylaxis by intradermal route and was similar to the WHO recommended rabies vaccine (Rabipur) of demonstrated efficacy.

Assessing safety and immunogenicity of post-exposure prophylaxis following interchangeability of rabies vaccines in humans.

Rabies post exposure prophylaxis with cell culture vaccines by either intramuscular route or intradermal route spans over a period of one month. World Health Organization recommends completing post exposure prophylaxis against rabies with the same cell culture or embryonated egg rabies vaccine and with same route of administration and any deviation from this shall be an exception. In the present study, the safety and immunogenicity of rabies post-exposure prophylaxis was studied prospectively in 90 animal bite cases that had interchangeability of rabies vaccines either by route of administration or brand/type and such changes had occurred due to logistical/financial problems. Among them, 47 had change in route of administration from intramuscular to intradermal or vice versa and 43 had change in the brand/type of cell culture rabies vaccine. All of them had category III rabies exposure and received equine rabies immunoglobulin along with the rabies vaccine. None of the study subjects had any adverse reactions. The rabies virus neutralizing antibody titers was assessed by rapid fluorescent focus inhibition test and all the vaccinees had titers ≥0.5 IU per mL on day 14 which is considered as adequate for protection against rabies. Thus, the present study showed that, rabies post-exposure prophylaxis was safe and immunogenic despite changes in the route of administration and brand/type of rabies vaccine.