THE IMPACT OF RUBELLA IMMUNIZATION ON THE INCIDENCE OF RUBELLA, CONGENITAL-RUBELLA SYNDROME AND RUBELLA-RELATED TERMINATIONS OF PREGNANCY IN SOUTH AUSTRALIA

Objectives To describe the impact of rubella immunisation on the incid ence of rubella, congenital rubella syndrome and rubella-related termi nations of pregnancy in South Australia, and to identify factors assoc iated with a re-emerging problem. Design and Methods A population-base d descriptive study using data from South Australian notifications of disease, births and terminations of pregnancy, the rubella immunisatio n programme, antenatal rubella antibody screening and paediatric hospi tal case records. Setting South Australia (population 1.48 million peo ple; 20,000 births per year). Main outcome measures Incidence of rubel la (age-sex specific), congenital rubella syndrome and rubella-related terminations of pregnancy; antenatal rubella sere-positive rates; rub ella immunisation uptake rates. Results Rubella notification rates in 1990-1996 were significantly higher for males than females for ages 15 -34 years. There were five cases of congenital rubella syndrome notifi ed in 1980-1996 compared with at least 20 confirmed or compatible case s in 1965-1979. Rubella-related terminations of pregnancy are now rare , with the last termination for maternal rubella being in 1993. The an tenatal rubella sere-positive rate in 1995 was 96.7%, but was signific antly lower among Asian women born overseas (78.6% among those 30 year s or older). Vaccination uptake rates in schoolgirls decreased between 1990 and 1994 (91.2% to 86.9%). Conclusions Since the introduction of rubella immunisation, the incidence of rubella infection among women of reproductive age, and of rubella-related terminations, has fallen. Congenital rubella syndrome has not been notified since 1990 but its r isk persists with a recent increase in rubella notifications, a fail i n school immunisation rates, a relatively low antenatal sere-positive rate among older Asian women born overseas and the trend towards givin g birth at older ages. Effective immunisation programmes must be maint ained, particularly in schools and for young children and migrant wome n.