PARENTS who dread having their baby vaccinated will be relieved to learn that the number of injections needed can be reduced. At present babies are given vaccines for Hib (Haemophilus influenzae bacterium) and DPT (diphtheria, pertussis and tetanus) in separate limbs - a total of six injections during the first four months. The Medicines Control Agency has now announced that three injections of a combined Hib-DPT vaccine are just as safe and effective.