Background: In February 2009, a cluster of rubella cases was recognized in Austria occurring between calendar weeks 3 and 7, 2009 after a long period of low rubella virus activity. A nationwide 2-dose measles, mumps, and rubella vaccination program had been introduced in 1994 to prevent this childhood illness.
Methods: An epidemiologic investigation was conducted to describe the cluster by time, place, and person. A confirmed outbreak case was defined as a febrile person (1) with generalized rash, which was laboratory confirmed or epidemiologically linked to a laboratory confirmed case and (2) who became ill after October 1, 2008 in the 2 affected provinces. A probable outbreak case was defined as any person meeting the clinical criteria of rubella and meeting the criterion 2 of a confirmed outbreak case. All cases were telephone interviewed on demographics and vaccination status.
Results: A total of 355 outbreak cases (including 247 confirmed cases) occurred in 2 neighboring Austrian provinces from mid-October 2008 until the end of June 2009, peaking in mid-March. The 2 most-affected age groups were 15 to 19 (44.4%) and 20 to 24 year olds (32.4%). The vaccination status was available for 230 cases; 10% of cases had received 1 measles, mumps, and rubella vaccine dose. No case had received 2 doses. Of the 146 female cases, one laboratory-confirmed rubella infection in a pregnant 18-year-old native Austrian resulted in elective abortion.
Conclusions: These findings underline the waning epidemiologic role of children in maintaining the circulation of rubella virus and indicate that additional vaccination activities targeting >15 year olds are needed to achieve the 2010 WHO target for rubella elimination in the European Region.