The European Sero-Epidemiology Network: standardizing the enzyme immunoassay results for measles, mumps and rubella

The ESEN (European Sero-Epidemiology Network) project was established to ha rmonize the seroepidemiology of five vaccine preventable infections includi ng measles, mumps and rubella in eight European countries. This involved ac hieving comparability both in the assay results from testing in different c entres and also sampling methodology. Standardization of enzyme immunoassay results was achieved through the development of common panels of sera by d esignated reference centres. The panels were tested at the reference labora tory and then distributed to each participating laboratory for testing usin g their routine methods. Standardization equations were calculated by regre ssing the quantitative results against those of the reference laboratory. O ur study found large differences in unitage between participants, despite a ll using an EIA method standardized against an international or local stand ard. Moreover, our methodology adjusted for this difference. These standard ization equations will be used to convert the results of main serosurvey te sting into the reference country unitage to ensure inter-country comparabil ity.