Rubella surveillance to December 1992: second joint report from the PHLS and National Congenital Rubella Surveillance Programme.

The high uptake of measles/mumps/rubella vaccine since October 1988 has had a major impact on rubella susceptibility in children under five years of age, with interruption of the epidemic cycle and reduction in incidence to a low endemic level. The number of infections in pregnancy reported in England and Wales to the PHLS Communicable Disease Surveillance Centre fell to 23 in 1990, and to 12 and two, respectively, in 1991 and 1992. The reduction was greatest in parous women, a group who were previously at risk through exposure to their own children. During 1991, however, susceptibility in parous antenatal women rose from 0.7% to 1%, suggesting that post-partum immunisation rates may have declined recently. If continued, this could give rise to outbreaks of congenital rubella in the future during the brief periods of rubella resurgence expected before disease elimination is achieved. Susceptibility among Asian women was four times higher than among non-Asians. Of the total of 94 births of congenitally infected infants since January 1987, only 19 occurred during 1990-92 (but this may increase due to late diagnoses). Factors contributing to the continuing occurrence of congenital rubella include missed opportunities for immunisation at school or post-partum, maternal reinfection, and recent immigration into the United Kingdom. Twenty-two (24%) of the women giving birth to congenitally infected infants since 1987 were Asian or Oriental women, of whom at least three acquired their infections abroad. Imported cases will be distinguished in future surveillance reports.