i believe the reason it is given at birth or in infancy is because this is the best time to immunise. if parents decide they want to immunise their children then they tend to stick to the schedule and get it done. it has nothing to do with racial or socioeconomic groups, that is a very presumptious statement to make, and suggests that poor people, or poeple from a certain ethnic group are more likely to participate in high risk behaviours. obviously bub won't however no one knows what they will choose to do when they are older, so if the hep B is given in childhood and they are immune, it saves them contracting hepB, with all the associated problems that comes with it, passing it onto other people, and costing the health system lots of money.