As reported by other authors, the most important factor associated with a lower immunity rate, was found to be increased age [2, 15, 16]. The reason for this is probably due to a combination between the lack of systematic vaccination before 1962, increased life expectancy and lack of administration of the recommended tetanus booster, the decline of tetanus protective antibody levels as age increases, and a deficient immune response to vaccine associated with immunosenescence [14, 15, 17, 18, 19, 20].
These data confirm the fact that the elderly are the population more at risk since they are less covered by the vaccine, and we can therefore say that the analysed group of patients is representative of the Italian reality as described by the Italian Ministry of Health [16].
For what concerns the category of patients older than 60 years, it is possible to denote a difference among males and females for what concerns the immunization rates (Figure 2).
In particular, a slightly higher percentage of male patients of this class (12%) were protected against tetanus, with respect to female patients (3.7%). In the next years, in Italy, this finding could undergo a significant change, with a reduction in the difference between males and females aged 60 years or more. This, due to the fact that the Military Service is not obligatory anymore since 2005 [21], but also to the introduction of the obligatory vaccination schedule in 1968 [22], and to the more recent law [23, 24], which reaffirms that for the individuals of age comprised between 0-16 years old, a series of vaccinations has to be rendered mandatory and administered without charge. There will therefore be a greater homogeneity between elderly males and females.
Although the low prevalence of immunization among the elderly can be justified by the aforementioned historical reasons, a more unsettling finding is the one of younger people lacking protective antibody levels.
It is important to focus on the fact that the vaccination against tetanus in Italy is currently mandatory at 3 months, 5 months, 11 months and 6 years in individuals born from 2001 on. A second booster dose is mandatory at 12-18 years for individuals born from 2001 on. Afterwards, Tdap is recommended every 10 years from age 19, and also for pregnant women in the third trimester (ideally 28 weeks) [25, 26]. It is therefore astonishing that even the subset of patients aged 0 to 18 years has been partially found to be unprotected against tetanus infection.
The lower rates of protection present even among the younger patients, might be due to factors such as a lack of knowledge about the importance of prevention of this disease through a complete cycle of vaccinations, as well as a lack of awareness on the necessity to receive boosters once completed the primary immunization series. This is probably a consequence of the fact that tetanus is currently one of the most underestimated and less well-known possible complication of a wound.
Another issue which could be important when considering high risk groups populations, is the one of immigration. Even though Pavia is not as cosmopolitan as other cities that have been taken into account by other studies, such as Rome and Brussels, the increase in the number of migrants from other countries in which the healthcare system is not so developed, may be partially responsible for the decrease in vaccination coverage over the next years. In this study, it was not possible to underline major differences for what concerns the difference in immune coverage among patients of different nationalities, due to the small sample of foreign patients (34 units). However, this investigation could be an interesting topic on which to conduct subsequent researches.
In order to increase the prevalence of immunization among patients, prevention should be done, as suggested by the Ministerial Circular concerning the recent Decree Law [27], by promoting vaccinations both for newborns, and more aged patients who somehow did not complete the primary vaccination schedule. A better compliance to vaccine coverage, has also been demonstrated to be associated with fewer hospital admissions in children [28].
Prevention should be done both through notifications under the form of letters, emails, leaflets, but also in a more direct way when the patient presents to the hospital, or to the cabinet of the general practitioner.
Patients should be made aware of the importance of keeping track of their own immunization status, and of remembering the date of the last administration of the vaccine, and if necessary, the date of the following booster. Moreover, it would be extremely important to more comprehensively educate patients on the topic of vaccines and vaccine preventable infections, stressing on the fact that some of these infections could quickly lead to major complications, and eventually result in the death of the individual.