Rubella is usually a mild disease with nonspecific symptoms, but can cause congenital rubella syndrome (CRS) when infection occurs during pregnancy. The objective of this study was to evaluate the sensitivity and positive predictive value of different data sources used for surveillance purposes in the Rubella Elimination Program of Catalonia between 2002 and 2011. The Urgent Notification to the Statutory Disease Reporting System, the Individualized Disease Reporting System, screening for other viruses included in the Measles Elimination Program, the Microbiological Reporting System and the Minimum Hospital Discharge Data were evaluated. 100 suspected cases of postnatal rubella and 6 suspected cases of CRS were detected. For postnatal rubella, Urgent Notification had the highest sensitivity (32.5%; 95%CI 18.6-49.1), followed by the Virus screening in Measles Elimination Program (25%; 95%CI 12.7-41.2). Virus screening in the Measles Elimination Program had the highest PPV (76.9%; 95%CI 46.1-94.9), followed by the Individualized Disease Reporting System (57.1%; 95%CI 28.9-82.3). For CRS cases, the Individualized Disease Reporting System had the highest sensitivity (100%, 95%CI 29.2-100) and the highest PPV (60%; 95%CI 14.7-100). Most confirmed postnatal cases (25 cases, 48.1%) were in the 25-44 y age group followed by the 15-24 y age group (11 cases, 21.2%). The highest values of sensitivity and PPV for the detection of confirmed cases corresponded to activities that were specifically introduced in the measles and rubella elimination programs.
Keywords: MMR vaccination; measles elimination; positive predictive value; rubella elimination; sensitivity; surveillance.