The status of rubella immunity among pregnant women in Kuwait: screening in childbearing age should be reintroduced

Synthesis of Evidence to Characterize National Measles and Rubella Exposure and Immunization Histories

Population immunity depends on the dynamic levels of immunization coverage that countries achieve over time and any transmission of viruses that occur within the population that induce immunity. In the context of developing a dynamic transmission model for measles and rubella to support analyses of future immunization policy options, we assessed the model inputs required to reproduce past behavior and to provide some confidence about model performance at the national level. We reviewed the data available from the World Health Organization (WHO) and existing measles and rubella literature for evidence of historical reported routine and supplemental immunization activities and reported cases and outbreaks. We constructed model input profiles for 180 WHO member states and three other areas to support disease transmission model development and calibration. The profiles demonstrate the significant variability in immunization strategies used historically by regions and member states and the epidemiological implications of these historical choices. The profiles provide a historical perspective on measles and rubella immunization globally at the national level, and they may help immunization program managers identify existing immunity and/or knowledge gaps.

Systematic Review of Measles and Rubella Serology Studies

Serological tests provide information about individual immunity from historical infection or immunization. Cross-sectional serological studies provide data about the age- and sex-specific immunity levels for individuals in the studied population, and these data can provide a point of comparison for the results of transmission models. In the context of developing an integrated model for measles and rubella transmission, we reviewed the existing measles and rubella literature to identify the results of national serological studies that provided cross-sectional estimates of population immunity at the time of data collection. We systematically searched PubMed, the Science Citation Index, and references we identified from relevant articles published in English. We extracted serological data for comparison to transmission model outputs. For rubella, serological studies of women of child-bearing age provide information about the potential risks of infants born with congenital rubella syndrome. Serological studies also document the loss of maternal antibodies, which occurs at different rates for the different viruses and according to the nature of the induced immunity (i.e., infection or vaccine). The serological evidence remains limited for some areas, with studies from developed countries representing a disproportionate part of the evidence. The collection and review of serological evidence can help program managers identify immunity gaps in the population, which may help them better understand the characteristics of individuals within their populations who may participate in transmission and manage risks.

Rubella Immunity among Pregnant Women in Jeddah, Western Region of Saudi Arabia

To determine the presence of rubella immunity among pregnant women attending their first prenatal visit in Jeddah, Saudi Arabia, a retrospective, descriptive, cross-sectional, hospital-based study (prevalence study) was undertaken. A total of 10276 women attending prenatal clinics between January 1, 2008, and December 31, 2011 were included. Rubella screening tests (immunoglobulins: IgG and IgM), rubella antibody titer levels, patient age, gravidity, parity, and the number of previous abortions were analyzed. No patients tested IgM positive, and 9410 (91.6%) were immune (IgG positive); the remaining 866 (8.4%) were susceptible. There were no significant differences in gravidity, parity, or the number of previous abortions between immune and nonimmune groups. In contrast, the immunity rate decreased with increasing age, with a significant difference between the youngest age group (15–19 years) and the oldest age group (40–49 years) (P = 0.0005; odds ratio, 2.86; 95% confidence interval, 1.7–4.7). Rubella immunity among pregnant women was high (91.6%) but decreased significantly with increasing age. A possible explanation for this is the change in the rubella vaccination policy in Saudi Arabia in 2002, from 1 dose to 2 doses. In addition, antibody levels begin to decline after vaccination and natural infection.

A relatively high number of pregnant women in Kuwait remain susceptible to rubella: a need for an alternative vaccination policy

OBJECTIVE

To measure the prevalence of anti-rubella IgG and hepatitis B surface antigen (HBsAg) among pregnant women in Kuwait in order to assess the effectiveness of the current vaccination programs.

SUBJECTS AND METHODS

This retrospective study involved 4,062 pregnant women evaluated in health centers in the Hawalli Province of Kuwait. They were screened for anti-rubella IgG and HBsAg using commercially available assays. The data were obtained from medical laboratory records.

RESULTS

The mean age of the pregnant women was 29.2 ± 5.26 years (range 17-49). The rubella IgG prevalence among the pregnant women was 88.4% (n = 3,589); 276 (6.8%) of the pregnant women had no antibody to rubella, and 197 (4.8%) had rubella antibody levels ≤10 IU/ml. Therefore, 473 (11.6%) of the pregnant women were susceptible to rubella. The proportion of susceptible women increased with increasing age from 3.4 to 10.3% and from 3.4 to 6.7% among women aged <20 years and those aged ≥40 years, respectively (p = 0.016). The prevalence of HBsAg was 0.3%, and it did not vary with age.

CONCLUSION

The prevalence of both anti-rubella IgG and HBsAg among pregnant women in Kuwait was relatively high. However, about 11.6% of pregnant women in Kuwait remain susceptible to rubella infection and hence congenital infection and fetal malformation.

Seroprevalence of rubella among Jordanian women of childbearing age

This study was conducted to assess immunity (seroprevalence) to rubella among Jordanian women of childbearing age. A multistage cluster sampling was used to recruit 1125 women of childbearing age (15-49 year) from the 12 Governorates of Jordan. Anti-rubella antibody titers were measured using enzyme-linked immunoassays. The overall immunity rate to rubella among women in childbearing age was 90.9% (CI: 88.8-92.9). However, the immunity rate was significantly lower in younger women aged 15-19 years (83%) compared to the whole cohort (P</=0.001) which means potential increased risk for congenital rubella syndrome (CRS). Immunity rates did not differ between regions and between urban and rural areas. Since the main priority is to decrease CRS among relatively susceptible cohorts, we recommend modifying the existing Expanded Program on Immunization with inclusion of a second dose of rubella vaccine at school entry (6 years of age) to decrease circulation of the virus among susceptible young females. We also recommend yearly catch-up school vaccination of young females entering the 10th grade for the next 10 years. Strengthening of rubella and CRS surveillance programs is also recommended in parallel with pre-marriage counseling regarding rubella and CRS for young females.