Duration of immunity to measles, rubella and mumps during the first year of life.

INTRODUCTION AND OBJECTIVES: The MMR vaccine was included in the official vaccination schedule in Spain in 1981. Currently, most women of childbearing age are vaccinated and have not been naturally infected. Several studies have shown that vaccinated women have a lower antibody concentration than that achieved after natural infection, and a shorter duration of transplacentally acquired antibodies in their children. The objective of this study was to determine the antibody titer in mothers and their infants at birth and throughout the first year of life under current epidemiological circumstances. MATERIAL AND METHODS: Single-center, observational, descriptive and prospective study conducted between October 2013 and December 2014. One sample of serum and another of a dried blood spot on filter paper were taken from each mother. Dried blood spot samples on filter paper were taken from the children at birth, and at 3, 6, 9 and 12 months. In all the samples, levels of antibodies to the measles, rubella and mumps viruses were measured using standardized quantitative assays. RESULTS: 146 mother-child pairs were included. 78.4%, 86.9% and 67.1% of mothers had antibodies to measles, rubella and mumps, respectively. A decrease in the antibody titer in children was observed after 3 months, and no antibodies against the three diseases were detected by the age of 6 months. Comparisons revealed no statistically significant differences between the antibody titers of children of mothers born before or after 1981 during the first year of their life. DISCUSSION: The rapid loss of transplacentally acquired antibodies against measles, rubella and mumps, under current epidemiological conditions, suggests that bringing the MMR vaccination forward to 9 months might be justified. Larger population studies are needed to confirm these results.