Early waning of maternal measles antibodies in era of measles elimination: longitudinal study

Objective To investigate the duration of the presence of maternal antibodies to measles in infants. Design Prospective study (May 2006 to November 2008). Setting Five hospitals in the Province of Antwerp, Belgium. Participants Of 221 pregnant women recruited, 207 healthy woman-infant pairs were included-divided into a vaccinated group (n=87) and naturally immune group (n=120), according to vaccination documents and history. Main outcome measure Measles IgG antibodies measured by enzyme linked immunosorbent assay (ELISA) at seven time points (week 36 of pregnancy, birth (cord), and 1, 6, 9, and 12 months); decay of maternal antibody in infants modelled with linear mixed models. Results Vaccinated women had significantly fewer IgG antibodies (geometric mean titre 779 (95% confidence interval 581 to 1045) mIU/ml) than did naturally immune women (2687 (2126 to 3373) mIU/ml) (P