[Current perspectives in virology: prevention].

A short review of deficiencies in immune reactions in older adults resulting in an increase of vaccine-preventable diseases (e.g. influenza) in this age group is presented. Reasons for so-called vaccine failures (primary, secondary) in persons previously vaccinated against measles are discussed. The immune status against poliomyelitis of the population in Germany, based on repeated serosurveillance studies is presented, the immunity of persons previously TOPV-vaccinated against a poliovirus type 3 variant (Finland) is demonstrated.