Adolescent immunization.

During the last century National Immunization Program (NIP) were implemented worldwide. The program started with a small number of vaccines for universal administration to infants and young children. In the second half of the century an evolution (slow in the start and rapid later) occurred in the structure of NIPs especially in developed countries. NIPs were enriched with new and more effective vaccines and expanded to adolescents and adults. The Adolescent Immunization Program (AIP) developed its own instructions and schedule that are continuously revised to improve further its efficacy. AIP composes of three main parts: a) the administration of novel vaccines produced for exclusive use in adolescents, b) the catch up process to supplement incomplete pediatric immunization schedule and c) the coverage of high risk groups with the appropriate vaccines. The novel vaccines for adolescent immunization are: the human papillomavirus (HPV2 and HPV4), the conjugated meningococcal with serotypes A, C, Wand Y, (MCV4), and the adult type of tetanus - diphtheria-pertussis (Tdap). Even in developed countries adolescent immunization is still below the desirable rates, critical for the prevention of diseases covered by the program. Thus at present a major challenge for adolescent immunization programs of developed countries is improvement of compliance to achieve and maintain high vaccination rates, for this age group, to provide an overall public health benefit.