Seroprevalence of low rubella IgG antibody levels among antenatal women in England tested by NHS Blood and Transplant: 2004-2009. Is rubella susceptibility increasing?

Antenatal testing for rubella susceptibility is undertaken to identify women at risk of exposure during pregnancy and to target post-partum immunisation. To evaluate the current rubella control programme and to inform future planning, data on anti-rubella IgG levels in antenatal sera tested by NHS Blood and Transplant were reviewed. The frequency of women with anti-rubella IgG <10 IU/mL increased by 60% over the 6-year study period and rates were significantly higher among younger women. The screening cut-off level of 10 IU/mL, used to identify women at risk, was determined in 1995 on the basis of early epidemiological studies and the correlates for protection now need review to support the appropriate management of a young immunised antenatal population. Ethnic minorities continue to be at increased risk of rubella susceptibility reinforcing the need to identify and opportunistically immunise these women.