Adolescents and vaccines in the western world

Recent data have shown that the immune protection evoked by vaccines given in the first years of life progressively weakens, and that this is associated with a higher than expected incidence of vaccine-preventable diseases in adolescents and young adults. Furthermore, the greater circulation of pathogens among adolescents and young adults leads to a high risk of infection in unvaccinated or not fully vaccinated younger children. These findings, together with the availability of vaccines specifically developed to prevent infections that typically occur during adolescence, have induced a number of experts to suggest radical changes in the immunisation schedules usually recommended by health authorities. The most important of these relate pertussis, meningococcal and human papillomavirus vaccines but, although they are based on unexceptionable scientific premises, the suggestions have been only slowly and partially received in most countries, even in those in which vaccination programmes are usually adequately implemented and monitored. Adolescence is a particular period of life characterised by changes in intellectual, moral, physical, emotional and psychological development. All of these can have a considerable impact on compliance with immunisation schedules because the approach to any preventive method no longer entirely depends on parents' and pediatricians' judgements as in the first years of life but is the consequence of a more complex process involving the adolescents' thoughts and opinions, their relationships with their parents, friends and physicians, and the information they receive from the mass media. Every effort should be made to overcome the barriers to adolescent immunisation, including those arising from the adolescents themselves.