Congenital Rubella Syndrome: Progress and Future Challenges

Rubella Vaccination During Pregnancy

As described previously, during the national vaccination campaign against rubella started in May 2001 in Costa Rica, in which the MR vaccine was administered to all men and women between 15 and 39 years of age, a follow-up protocol for women who were vaccinated whilst unknowingly pregnant was elaborated to assure appropriate follow-up of all inadvertently vaccinated pregnant women and their children.

To classify the prevaccination maternal immune status, Costa Rica used standardized algorithms based on serum sample to detect IgM and IgG rubella antibodies using ELISA techniques. All newborns were evaluated by pediatricians using standardized procedures to detect any defect associated with rubella infection.

A total of 3810 women vaccinated during the first 3 months of pregnancy were reported to the National Surveillance System (6.7% of all pregnant women). A case-control analysis including 1191 mothers and their newborns was performed. No cases of CRS were detected and the rates of miscarriages and stillbirths were similar to the reported national rates. No significant statistical association was found between rubella vaccination during pregnancy and fetal defects. Adjusted odds ratio (OR) of defects compatible with CRS were 1.09 (95% confidence interval [CI]: 0.34-3.54), with abortion were 0.60 (95% CI: 0.26-1.39), with stillbirth were 1.32 (95% CI: 0.10-16.81), with prematurity were 0.25 (95%CI: 0.03-2.39) or with low birth weight were 0.25 (95% CI: 0.03-2.23).^[20]

Canada reported rates of 3.7% and 3.4% CRS-compatible clinical manifestations in cases and controls, respectively.^[21] The frequency of the compatible CRS defects in the Costa Rican study ranged from 4.0-5.4%. All defects were associated with congenital infections, such as cytomegalovirus or syphilis, as well as neurodevelopmental retardation attributable to genetic disorders.

In 2001, the Advisory Committee on Immunization Practices of the USA reported that no single case of CRS was identified among 680 live births from susceptible vaccinated mothers during the first trimester of gestation with rubella vaccines (HPV-77, Cendehill or RA 27/3).^[22] Despite the scientific literature not reporting a real risk of CRS after rubella vaccination during pregnancy,^[23] a theoretical risk of 0.5% has been estimated if the vaccine is administered during the first trimester and a maximum of 1.3% if applied between 1-2 weeks before and 4-6 weeks after conception. Overall, the estimated theoretical risk of severe malformations attributed to the RA 27/3 vaccine against rubella varies between 0 and 1.6%.^[24]

The Costa Rican experience supports the scientific evidence and literature, stating an absence of risk associated with the administration of the vaccine before conception or during gestation. The main reason to maintain the contraindication of administering rubella vaccine during pregnancy is to avoid its potential association with congenital defects not related to the vaccine itself.

Cite this: Congenital Rubella Syndrome: Progress and Future Challenges - Medscape - Mar 01, 2009.

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