Early waning of maternal measles antibodies: why immunization programs should be adapted over time.

Primary protection against measles in the first months of life is provided by transferred maternal antibodies. Since the introduction of the measles vaccine, changes in epidemiology have had major effects on the transmission of protective antibodies. The majority of women of childbearing age are now vaccinated and transfer fewer antibodies than naturally immune mothers, conferring shorter protection to their offspring. This article reveals an early loss of maternal antibodies in infants of vaccinated mothers but also in infants of naturally immune women. This increasing susceptibility window between loss of maternal antibodies and vaccination should be taken into account for a timely administration of the first dose of measles vaccine, particularly in the current context of re-emerging measles in Europe. Additional programs are needed to improve vaccination coverage within the global population and to reduce the spread of measles.