[Age-related loss of maternal antibodies against measles in children in La Plata].

Measles outbreaks every 3-4 years have occurred in Argentina. The vaccine was introduced in 1978 as part of a regular program, and the age for the first vaccination was changed to one year old. The optimal age for first measles vaccination is defined as that age with the highest proportion of infants responding to the vaccine. It is dependent on the presence of maternal antibodies against measles virus and the maturation of the immune system. This paper reports the loss of maternal antibodies in infants from vaccinated mothers, attending at the Hospital I.A.E.P. Superiora Sor María Ludovica, La Piata, Argentina. To determine the IgG antibodies against measles virus, an ELISA test was used in a longitudinal follow up of 48 patients (4, 6 and 9 month-old infants). Only 18.7% of 4 month-old infants showed detectable levels of IgG antibodies against measles virus; this value declined to 4.2% in 6 month-old infants (p < 0.01) and measles virus antibodies were undetectable in 9 month-old infants. The extension of this study to a broader population is suggested, in order to reconsider the optimal age of the first measles vaccination.