The STIKO recommends that persons without an underlying disease between the ages of 18 and 59 should have basic immunity. This is achieved from at least three antigen contacts, of which at least two should have occurred through vaccination. For risk groups, persons over 60 years of age, persons with an occupationally increased risk of infection, persons in need of care as well as relatives or close contacts, further booster vaccinations are recommended in addition to the basic immunity. These should be given at least 12 months after the last antigen exposure. For immunodeficient individuals, additional vaccinations at shorter intervals may be appropriate. No vaccinations are currently required for healthy children and adolescents under 18 years of age. Further information is provided by the RKI