[Vaccines: from the identification of the microorganism to marketing. How long does it take?].

The development of a vaccine, particularly one that can help against the recent pandemic, is a topic that has recently attracted public opinion. More than ninety vaccines are currently being developed against Sars-Cov2 by universities and companies around the world. They are protein-based vaccines, viral vector vaccines, DNA or RNA vaccines and inactivated or attenuated viral vaccines. The development of a vaccine starts from the identification and characterization of the microorganism that causes the disease. The second step is the preclinical phase. Then, there is the phase of clinical experimentation, which allows to study the posology, efficacy and safety of the vaccine, on an increasingly larger sample. In the European Union, vaccines are authorized through two procedures (EU and national) based on the quality, safety and efficacy requirements defined by the European and international guidelines. Timing of realization, authorization and marketing of new vaccines can be shortened in cases of particular need, through an accelerated evaluation known as "Priority Medicines". In this period, it is crucial not to neglect current vaccinations. In fact, during the pandemic period, many countries postponed vaccination campaigns against many vaccine-preventable diseases, causing a marked decrease in routine immunizations in childhood.