[Mumps: efficacy of booster immunization].

10 children aged 15 years, who presented with anti-mumps antibodies of < 3 PEI (Paul Ehrlich Institute) despite documented mumps vaccination in the past, were boosted with Triviraten Berna (Rubini mumps strain) and the antibody response was assessed after 7, 28 and 90 days. All 5 children boosted with the same vaccine (Rubini mumps strain) had a titer rise as early as day 7 persisting for 3 months. The 4 children primed with the Jeryl Lynn mumps strain showed a primary immune response, i.e. a rise of the antibody titer after 28 days only, which did not persist well. The child originally primed with the Urabe mumps strain did not show any significant immune response on day 28, which means a negative result. Children apparently susceptible to mumps cannot be differentiated from immune children by measurement of antibody titers. Reexposure to the homologous vaccine virus elicited a persisting immune response: however, revaccination with a heterologous vaccine virus elicited an immune response directed against different antigenic epitopes, followed by limited persistence of circulating antibodies. The efficacy of a second dose of mumps vaccine was demonstrated in 9/10 children. Only by using a two-dose immunization schedule is it possible to effectively avoid the occasionally serious complications of this viral infection, as has been achieved in Finland.