The scientific and social value of vaccination

Vaccination is one of the most important scientific discoveries in the history of medicine and has contributed in a fundamental way to increasing the life expectancy of human populations.

Vaccination is one of the most important scientific discoveries in the history of medicine and has contributed in a fundamental way to increasing the life expectancy of human populations.

On the one hand, progress in knowledge has clarified the modes of action of vaccines, whose application was initially carried out on an experimental basis. Progress made over the past decades, in the areas of bacteriology, virology, immunology and mathematical modelling applied to infections, have opened up new horizons that were once unthinkable in the field of medical research1. Today, in addition to the ever-increasing availability of new vaccines against infectious diseases, research on vaccines against cancer, hypertension, degenerative diseases of the nervous system and against addictions are flourishing.

Vaccination has been defined as one of the greatest medical discoveries ever made by man, comparable in importance, given its impact on health, to supplying drinking water to the population2.

For this reason, vaccinations are evaluated from a scientific point of view and their large-scale application taken into account, given their benefits in terms of epidemiological and clinical results.

The mode of action of vaccines is represented by active immunisation against infections, obtained by exposure to a very small quantity of inactivated infectious agents: viruses or bacteria are killed or attenuated, or more often only parts of them are used. By mimicking a natural infection without causing disease they activate all the mechanisms of recognition and defence by the immune system, which will therefore be able to eliminate the pathogen when the immunised subject is exposed to infection.

Of course these mechanisms were not known when the first vaccine (smallpox: Edward Jenner 1749-1823) was introduced, as interventions of vaccination were at that time practiced according to an empirical principle. Only subsequently has the evolution of medical science clarified many of the reasons for the efficacy in controlled conditions (experimental studies) and in the field ("effectiveness") of vaccines. In particular, the discoveries in the field of bacteriology (starting with Louis Pasteur) and virology, between the end of the nineteenth and the first decades of the twentieth century, led to an ever wider opportunity to explain modes of action, but also to find new candidate vaccines for the prevention of dangerous infectious diseases. The development of cell culture systems for viruses in the late 1940s (thanks also to the Nobel Laureates Enders, Weller and Robbins) gave further impetus for research into inactivated and attenuated live virus vaccines.

If we reflect on the mechanisms of vaccinology and on its history, it seems amiss that some schools of thought today wish to oppose vaccinations with alternative medicines such as homeopathy, considering that vaccination, as we have seen above, is a homeopathic procedure par excellence. The founder of homeopathy himself (Samuel Hahnemann 1755-1843) asserts that similia similibus curantur: like is cured by like ie a disease may be cured with medicines that produce in the healthy subject the characteristic symptoms of that same disease. The difference is that vaccination, using the principle of “like" (as opposed to the principle of "opposites" philosophically attributed to traditional medicine) must precede the infection. Thus, one could even define vaccinology as a preventive homeopathic "science". The term "science" must be stressed, because beyond the disquisition as to whether the principle is philosophically "like" or "opposite" to disease, what matters is that it is effective and proven from a scientific point of view.

And it is precisely in the ever-evolving sector of immunology that vaccines see their scientificity demonstrated, both in the multiplication of the possibilities of interpretation of their own modes of action and in the increase of opportunities for new approaches to prevention and treatment.

Additionally, vaccines act as an excellent verification system for new breakthroughs in immunological science. The ideas regarding innate immunity that have been strengthening since the 1990s and especially in this last decade, starting with the studies of Janeway and collaborators3 have opened up innovative frontiers in vaccinology, above all with regard to the research and development of new systems of support for antigens used in vaccines. At the same time, the knowledge gained in recent years on the importance of regulatory t-lymphocytes (cells capable of suppressing immune system activation responses) already allow us to foreshadow future research on vaccines against autoimmune diseases. A further breakthrough, which will certainly see a development that is difficult to predict today in its many implications, is the release of vaccines from their traditional field of action as tools for the prevention of infectious diseases, to extend their range of interest to the treatment of chronic-degenerative diseases. Only in the future will we be able to verify all of the potential effects of the new immunological therapies being studied today, but already the multiple researches on the ‘vaccine’-based treatment for tumours (melanoma, breast cancer, non-small cell lung cancer etc.), for hypertension, Alzheimer's disease and the cessation of lifestyle habits (anti-nicotine and anti-cocaine vaccines) suggest a scientific future of great interest for the science of vaccination.

Moreover, it has already been established that the benefits of vaccination are not limited to clinical or epidemiological improvements, such as the prevention of diseases and their outcomes, with the resulting economic consequences, but they are also able to promote economic growth of countries as well as poverty reduction4.

Therefore, the economic value of vaccinations, in addition to the scientific one, is an aspect that at least theoretically should favour their maximum diffusion. Unfortunately, the economic crisis that is affecting industrialised countries has led to a necessary rationalisation of spending also in the health sector, with the consequent lower propensity to purchase and implement new vaccines, despite the evidence of their ever-increasing safety and effectiveness. In fact, the attention of the decision-makers tends to turn more towards a perspective of containment rather than towards an investment, with the result that vaccinations are immediately taken into consideration only if they generate savings from the point of view of the Health Service and if the return on investment is in the short term.

However, the social value of vaccination practices must also be added to its clinical-epidemiological and economic values.

Its social character has always been relevant, given that since the time of Edward Jenner vaccination has been widespread and has always been the subject of lively debate between supporters of its unequivocal positive effect and opponents (whose motivations are often of an ideological nature), at times due rejection by the authorities who should have recommended its use.

The phenomenon of community protection is obtainable for many vaccines if a high enough coverage is reached in the target population. More commonly known as "herd immunity", it has always represented an added social benefit of vaccination. Precisely for this reason, it must be inconceivable that the benefits of vaccination are not available in an equitable way to the entire population. This is also the historical reason for the policies of mandatory vaccination that have accompanied immunisations.

As often happens in the field of public health (an applied science in which the experimental approach was initially used to find concrete answers to health problems), large-scale adoption of preventive vaccination and observation of its exceptional effects on mortality and morbidities caused by lethal diseases (such as smallpox, rabies, plague, cholera, diphtheria and others) sometimes preceded proof of the mechanisms by which the vaccine establishes protection.

The social value of vaccination is reflected both on the individual and on the community. For most diseases, obtaining high vaccination coverage makes it possible to contain the spread of the micro-organism responsible and, consequently, guarantees protection for the community, that is even for those who are not vaccinated. The impact on the health of the population is therefore considerable in terms of limiting the damage caused by the disease or its complications (morbidity, mortality, recourse to medical treatment, hospitalisation) and the reduction of both direct and indirect costs.

Infectious diseases do not recognise geographical and/or political boundaries. Therefore all, but in particular those that can be prevented by vaccine, require a global and not merely local approach to their prevention and control: WHO’s great strives for the elimination or eradication of an infectious disease are often carried out on the basis of global vaccination strategies. These strategies necessarily require the elimination of ideological and political barriers, but also of economic and cultural obstacles, in favour of a collective and global approach in defence of the populations’ health.

The European Union also intends to encourage the development of a common European Public Health policy, since the phenomenon of globalisation tends to expand and the borders between EU countries will become less and less relevant.

In Italy the National Vaccination Plan (PNV) 2012-20145 is the document of reference in the field of vaccination. Among other things, the health objectives to be achieved through vaccination and the related strategies of choice are identified within. The 2001 amendment of Titolo V of the Constitution identified the areas of exclusive or concurrent legislation of the State and the Regions, stating that the protection of health must fall under concurrent legislation. The single Regions’ acquired autonomy of choice, both with regard to the terms of supply of some vaccinations and to the whether the vaccination should be free-of-charge or paid by the citizen, weakens the principle of fairness in the "right to health", considered a key element of the Italian health system. Health inequalities go against the common values of social justice, solidarity and equality of opportunity for the population. In fact, the coverage data show inequalities, both geographic and socio-economic, that are defined by the PNV itself as "unjust and unconstitutional".

In general terms, the reduction of health inequalities has not only an ethical significance but also an economic aspect: the costs of illness, disability and premature death represent enormous obstacles to the development and well-being of society.

Although these are shared concepts, the vaccination offer in the country is still inconsistent and in some ways unfair. On the one hand, there are Regions that believe that it is fundamental to evaluate priorities, pitting them against each other for the resources earmarked for preventive interventions, arguing their case that it is “better to focus resources on tackling the most significant health problems, such as the elimination of measles, instead of planning more recently-introduced vaccinations which are deemed less urgent". On the other hand, there are regions that believe that any vaccination that has been shown to be effective and safe should be made available for the protection of the population, especially children.

And yet, as far as the social aspect is concerned, vaccination is one of the highest-ranking health technologies based on cost per year of life gained and cases of illness avoided, ie spending on vaccines is one of the best and most profitable ways for society and the Health Service to invest the scarce resources available. Nevertheless, the immunisation campaigns unfortunately represent the Cinderella of Italian Health, accounting for less than one per thousand (0.1%) of the National Health Fund. This philosophy triggers an hourglass effect: those who invest more in vaccinations recoup more, also in human resources, training, technological equipment and credibility. The resources factor must be borne in mind, especially in a historical moment in which some Regions are in administration due to economic problems. While prevention is gaining increasing importance within the Health System, as an expression, among other things, of a shift in the health needs of the population, we are also witnessing a continuous depletion of resources. It is therefore necessary for Health Service Doctors, Paediatricians, and GPs to work together with the main members of society affected and involved, each according to their own possibilities, competences and responsibilities in order to favour the correct use of vaccines and to safeguard the undisputed social value of vaccination – the national heritage of all Italian citizens, regardless of social status and place of residence.

Sources / Bibliography
  1. Anderson, R. M.; May, R. M. Infectious diseases of humans: dynamics and control. Oxford and New York: Oxford University Press, 1991.
  3. Janeway CA Jr, Medzhitov R. Introduction: the role of innate immunity in the adaptive immune response. Semin Immunol 1998; 10: 349-350.
  4. Bloom DE. The value of vaccination. Adv Exp Med Biol. 2011;697:1-8.
  5. Gazzetta Ufficiale della Repubblica Italiana (Suppl. Ordinario del 14 aprile 2005)- Piano Nazionale Vaccini 2005-2007
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