With the current mandatory MR vaccine drive by the government in various states,  this needs to be addressed with sufficient scientific evidence backup, and at the same time logical reasoning that the lay public can understand, considering we live in an era of scandals and scams. What would be a satisfactory professional reply for a query regarding the reason/ justification for administering MR - Measles Rubella Vaccine in a child who has already been vaccinated with MMR vaccine in the past?