Combined vaccines. An important aim of WHO EPI is to increase the number of target diseases routinely included in infant vaccination schedules while simultaneously decreasing the number of injections required by combining more antigens in vaccines. Combined vaccines are urgently needed because of the increasing number of recommended vaccines for children. They could be considered as having the same priming effects as monovalent ones. They demonstrated a good reactogenicity and tolerability profile. Combined vaccines are more comfortable option for the infant vaccination providing immunity against four or more important childhood diseases with a single injection at each visit. The development of antibodies to polysaccharides of encapsulated bacteria such as Streptococcus pneumoniae, Haemophilus influenzae type B or to meningococcal bacteriaes in early life is poor. The newly introduced conjugate vaccines are widely recommended as highly protective vaccines in infants.