Assessing the relationship between antigenicity and immunogenicity of human rabies vaccines when administered by intradermal route: results of a metaanalysis.

The metadata of 10 published studies and 3 vaccine trial reports comprising of 19 vaccine cohorts from four countries conducted over a period of 23 years (1986 - 2009) was used for metaanalysis. The vaccines studied were purified chick embryo cell vaccine (Rabipur, India & Germany), purified vero cell rabies vaccine (Verorab, France; Indirab, India) & human diploid cell vaccine (MIRV, France).The potency of these vaccines varied from 0.55 IU to 2.32 IU per intradermal dose of 0.1 ml per site. The vaccines were administered to 1,011 subjects comprising of 19 cohorts and using five different ID regimens. The immunogenicity was measured by assays of rabies virus neutralizing antibody (RVNA) titres using rapid fluorescent focus inhibition test (RFFIT) [15 cohorts] and mouse neutralization test (MNT) [4 cohorts]. The statistical analysis of the data was done by Karl Pearson's correlation coefficient to measure the relationship between antigenicity and immunogenicity. It was revealed that, there was no significant linear relationship between antigenicity and immunogenicity of rabies vaccines when administered by intradermal route. (p> 0.230 and p>0.568).