Vaccines are biological products designed to induce a protective immune response, mimicking natural infection without the development of disease and / or complications. Combined vaccine administration and vaccines co-administration is a safe and effective practice, the benefits of which outweigh the disadvantages. The operators should assess individual variations for the completion of the vaccination schedule, which may be necessary in clinical practice, case by case. Often there are myths to dispel, such as fears about the overload of the immune system, the remora to do more injections in the same session, excessive reactogenicity and some false contraindications. The operators, in order to resolve their doubt in performing non-routine co-administrations, can rely on the Summary of Product Characteristics (SPC) of the individual vaccines and on the new available evidence.