Epidemiological changes in rubella IgG antibody levels detected in antenatal women from a retrospective rubella seroprevalence study.

Abstract

Rubella is caused by the rubella virus, a single-stranded RNA virus of the Togaviridae family. The most severe complications of rubella in adult women occur during pregnancy when infection can lead to miscarriage, stillbirth or congenital rubella syndrome. Antenatal rubella susceptibility screening is no longer performed in England, Scotland or Wales but continues in Northern Ireland. The aims of this seroprevalence study were to (1) determine amongst women presenting for antenatal care the percentage of women who are rubella susceptible, rubella immune and those with equivocal rubella antibody levels by year of birth and (2) to consider how rubella vaccination resources can best be utilised. A retrospective study was performed analysing all antenatal rubella IgG antibody tests performed between January 2015 and June 2017 inclusive (n = 19,000; excluding duplicate tests). All antenatal women were included regardless of the country of origin and age. From our analysis, 88.7% (n = 16,868) women had plasma concentrations of anti-rubella IgG > 10IU/ml. 7.3% of women (n = 1403) had rubella IgG levels between 5 and 9.99IU/ml, and 2.8% (n = 729) had IgG levels < 5IU/ml. A decline in rubella immunity in younger women was evident. This study has identified an increase in women who are rubella susceptible and women with equivocal rubella antibody levels. International evidence suggests that rubella serology is unreliable and antenatal screening does not confer any benefit to women during their current pregnancy. Consideration should be given to re-direct resources currently utilised for antenatal screening to facilitate the vaccination of pre-pregnancy and postpartum women and also to opportunistically offer vaccination to all women of childbearing age.