Immune response after primary and re-vaccination with different combined vaccines against measles, mumps, rubella

The humoral immune response after primary and re-vaccination confirmed the high immunogenicity of the combined vaccines used: "MMR-Vax(R)" "Pluserix(R)" and "Triviraten(R)". The investigation of paired serum samples of prevaccinal seronegative infants (n = 365) by an enzyme immune assay (Enzygnost(R)) exhibited seroconversion rates of >90-100% for all three components with the exception of the mumps component of "Triviraten(R)" (38%). However, by additional methods (plaque neutralisation test, immunofluorescence test) mumps antibodies could be detected in 93.4% of infants having received vaccine "Triviraten(R)". The mean values of antibody activities against the three components did not differ significantly after vaccination with "MMR-Vax(R)" and "Pluserix(R)". However, after vaccination with "Triviraten(R)" the mean antibody values were significantly lower (P < 0.01) against the measles strain "Edmonston-Zagreb" and especially lower (2-20 times) against the mumps virus strain "Rubini". Revaccination of pre-vaccinal seropositive schoolchildren and adolescents (n = 676) with "MMRVax(R)" and "Pluserix(R)" produced no different results. The rate of vaccinees responding with a booster reaction reached 68.4% for measles and mumps, but only 8.6% for rubella. A booster reaction could be observed in 100% of those vaccinees who had antibodies at a low level, also in the case of naturally acquired immunity. The low-level range for antibodies against measles was defined as 0.15 < 0.40 IU/ml, mumps 1:230 less than or equal to 1:500 and rubella 7-16 IU/ml. The rate of vaccinees with low-level antibodies against measles can become as high as 10%, for mumps 20% and for rubella 3%. The correlation between the level of antibodies and protection against the disease is discussed. The rate of individuals in a population with doubtful protection (unvaccinated, non-responder and low responder after primary vaccination) prevents to reach the herd immunity of 95% necessary for elimination. The results of our serological studies strongly recommend re-vaccination against measles, mumps and rubella. (C) 2000 Elsevier Science Ltd. All rights reserved.