The value of booster vaccinations against diphtheria, tetanus, pertussis and poliomyelitis.

Abstract

During the last ten years important achievements have been made throughout the world in the fight against infectious diseases, particularly those preventable by vaccination. the combined efforts of researchers, industry and health workers have made it possible to fully exploit the potential of the new vaccines, using them in the most rational way possible on the basis of the latest epidemiological data and objectives to be achieved. in italy, in common with other countries, precise objectives have been established in the fight against vaccine preventable disease, appropriate operating strategies have been developed and a vaccination schedule has been defined. this latter harmonises mandatory and recommended vaccinations and indicates the chronological sequence in which they should be performed. the vaccination calendar is an indispensable tool for achieving the objectives of the various immunisations uniformly throughout italy. it is vitally important that this vaccination schedule is updated on the basis of the latest scientific knowledge, the changed epidemiological situation of the various infectious diseases, possible changes in organisational requirements and, above all, the availability of new products [1, 2]. the success achieved so far against diseases for which mandatory vaccination exists (diphtheria, tetanus, polio and hepatitis b) is strictly related to the high levels of vaccination coverage reached and maintained nationwide. For recommended vaccinations, the situation is more diversified, although data from the latest iCONa survey show that in the case of antigens included in the hexavalent vaccines, high levels of vaccination coverage have been obtained (pertussis and Haemophilus influenzae type b). However, for measles, mumps and rubella, although a significant increase in vaccination coverage, the level critical for eliminating the diseases has not yet been reached [3, 4]. Over and above achievement of the established vaccination coverage objectives, the action taken over the years has influenced the epidemiology of the various diseases with a reduction in morbidity and generally a lower spreading of the corresponding infectious agents. in some cases, there are also problems associated with the length of protection provided by the vaccines and the consequent need not just to optimise vaccinations in newborns but also to plan booster vaccinations. these latter are essential to avoid the creation of clusters of newly susceptible subjects among adolescents and adults, previously successfully vaccinated, due both to the decay of immunity and the reduced spreading of microrganisms [5]. the 2005-2007 italian National Vaccination Plan (iNVP) has underlined the importance of reaching and maintaining high vaccination coverage rates in childhood; besides, the iNVP emphasizes that indications exist for booster vaccinations for tetanus, diphtheria, pertussis and polio, beginning from pre-school age and every ten years in adult life, as indicated by the current italian national vaccination schedule [6]. the practical indications are backed by Presidential Decree no. 464 of 7 November 2001 [7], which, modifying the provisions of the fourth clause of article 2 of Presidential Decree no. 1301 of 7 September 1965, states: • booster vaccinations with administration of tetanus anatoxin, possibly in combination with diphtheria anatoxin and/or other antigens, should be given at 10-year intervals; • in infants and children who begin anti-tetanus vaccination before the age of 7 (aged 6), the first booster should be given, with administration of tetanus anatoxin possibly in combination with diphtheria anatoxin and/or other antigens, 4-5 years after the last dose of the primary vaccination series. Subsequent boosters should be given at 10-year intervals.