Table 1 Immunizations schedule: main factors that should be taken into account

Epidemiological factors

• Typical age of acquistion of the disease (immunization should come first)

• Possible age-related complications of the disease

• Age-related adverse events of immunizaton

• Already implemented immunization programs

Immunological factors

• Immune system development

• Clearance of maternal antibodies

• Number of doses and time interval between doses necessary to obtain an effective immune response

• Duration of immune protection elicited by immunization

Practical factors

• Number of immunizations to be included in the schedule

• Availability of combined vaccines

• Number of vaccination sessions

• Organization of immunization services