Assessing the relationship between antigenicity and immunogenicity of human rabies vaccines. Results of a meta-analysis

A meta-analysis was done to study the relationship between antigenecity and immunogenecity of human rabies vaccines. The data of ten cell culture human rabies vaccine studies conducted at a single centre during 1993-2004 were used in the study. The vaccines studied included Purified Chick Embryo Cell Vaccine (Kaketsuken, Japan and Rabipur, India), Purified Vero cell Rabies Vaccine (Verorab, France), Human Diploid Cell Vaccine (MIRV, France and Rabivax, Adsorbed and Lyophilized, India) and Rhesus Diploid Rabies Vaccine (adsorbed, USA). Interestingly, it was revealed that an higher antigenecity of rabies vaccines viz. potency of > or = 5 IU per single intramuscular dose did not result in significantly higher immunogenecity, as measured by rabies virus neutralizing antibody (RVNA) titers in the vaccinees, both on day 14 (t = 0.42, p > 0.66, GMR = 1.06, 95% CI of GMR = 0.82, 1.37) and day 90 (t = 0.80, p > 0.43, GMR = 1.15, 95% CI of GMR = 0.74, 1.14). However, as there are no reports of meta-analysis of cell culture human rabies vaccine trials, to confirm this observation the authors recommend further studies in this regard.