Abstract :
The success of an epidemiological program against infectious diseases depends on an effective prophylactic vaccine. Although efficacy and effectiveness are used interchangeably, effectiveness depends upon efficacy. Few methods are in use to assess the efficacy of the vaccine, a randomized double blind controlled trial is the least ambiguous method for evaluation. Observational designs for vaccine efficacy include cohort and case control and are useful when comparing vaccines with very large effectiveness. Modeling helps in designing vaccine. Serologic responses to antigens in combination vaccine differ from those obtained with separate administration of the components. Creation of a vaccine advisory and control authority is imminent
