The prevention and avoidance of infectious diseases through vaccinations is considered one of the ten most important advances in medicine during the 20th century.

Vaccination protects through active immunization, that is, the process in which the administration of all or part of a microorganism or a modified product thereof can induce the production of antibodies and consequently protection similar to that afforded by natural disease.

Some vaccines provide almost complete and lifelong protection against the disease (measles, rubella), others only protect against severe manifestations (pneumococcus), while some must be repeated periodically to ensure protection (tetanus, pertussis).

The immune response to vaccination depends both on the characteristics of the vaccine and on the characteristics of the vaccinee, eg age, previous immunity, comorbidities and genetic characteristics.

In countries with organized vaccination programs, a significant reduction in the incidence of vaccine-preventable diseases has been observed, while multi-year and multifaceted surveillance leaves no room for questioning the safety of vaccines. The reduction recorded exceeds 95% for most diseases for which there are vaccines.

Smallpox has been eradicated since the late 1970s, polio is recorded with few cases in developing countries, while diseases such as diphtheria and tetanus account for few cases per year in countries with organized vaccination programs. Also typical is the example of meningitis caused by Haemophilus influenzae type b, which disease was accompanied by a particularly high mortality rate in the pediatric population.

The introduction of the vaccine in the late 1980s led to its almost disappearance in fully vaccinated children, completely changing the epidemiological data in all countries of the world. However, vaccines also have an anti-cancer effect, such as the impressive reduction recorded in cervical cancers after the introduction of the vaccine against the human papilloma virus (HPV) in girls.

Despite the obvious benefits, hesitancy towards vaccination shows an increasing trend worldwide, with the most frequent objections regarding the safety and less often the effectiveness of the vaccines.

Vaccines have fallen victim to their success, as the incidence of serious vaccine-preventable diseases has dropped dramatically with the result that both parents and often health professionals fail to recognize their potentially serious consequences.

Other factors that historically reduce child embolization rates are war, disruption of social cohesion, and economic poverty. Very recently, the pandemic of the COVID-19 infection has caused a significant reduction in vaccination coverage worldwide, which has led to the recent outbreak of measles and whooping cough.

The quiver of prevention has never been stronger than today and is expected to strengthen further in the coming years. The development of new technologies has also borne fruit in the field of vaccinations. Pediatricians have the extraordinary fortune, but also the enormous obligation, to deliver generations of children protected from many and serious diseases, generations of healthier adults.