Agreement of rubella IgG antibody measured in serum and dried blood spots using two commercial enzyme-linked immunosorbent assays.

Cases of congenital rubella are now rare in the United Kingdom. However, in certain areas such as London, where a significant proportion of pregnant women has been born abroad and uptake of trivalent measles-mumps-rubella (MMR) vaccination is low, the risk of a rubella outbreak remains. Prior to carrying out a seroprevalence study using rubella IgG antibody in newborn dried blood spots as an indirect marker of maternal immunity, rubella IgG antibody concentrations in serum and dried blood spot samples were investigated. Anonymous paired serum-dried blood spot samples left over from occupational health screening were tested for rubella IgG antibody by two commercially available enzyme-linked immunosorbent assays (ELISAs) (Dade Behring, Marburg, Germany, and Diesse, Siena, Italy). Agreement between serum samples and dried blood spot samples was high for both assays. There were no significant differences in antibody concentrations in paired samples, as 67 of 73 samples tested with the Diesse ELISA (91.8%), and 76 out of 79 samples tested with the Dade Behring ELISA (96.2%) were within two standard deviations of the mean difference. Commercial ELISAs are an appropriate test for seroprevalence surveys based on rubella IgG in dried blood spot samples.