Global Vaccine Safety

Pregnancy outcomes after inadvertent immunization with rubella vaccine

Extract from report of GACVS meeting of 18-19 June 2008, published in the WHO Weekly Epidemiological Record on 8 August 2008

A large amount of data are available on pregnancy outcomes among women inadvertently immunized with rubella vaccine in multiple countries (Germany, the Islamic Republic of Iran, the United Kingdom and the United States). These data arise from both retrospective and prospective cohorts, as well as case–control studies done in the context of routine administration or mass vaccination campaigns. The time of vaccination in relation to the time of conception varied across studies. No neonates were found to have congenital rubella syndrome despite evidence that a few had infection with vaccine virus (defined as immunoglobulin M [IgM] positivity).

The GACVS also considered newly reported data from 5 Latin American countries (Brazil, Costa Rica, Ecuador, El Salvador and Paraguay). A total of 29 663 women who had been inadvertently vaccinated were identified; 3264 of them were susceptible to rubella. Of those who were susceptible, 2236 were followed. By IgM measurement, 68 (3%) potential foetal infections were identified, none of which manifested as congenital rubella syndrome. No increased risk of additional abnormalities was detected when compared with expected background rates of congenital malformation in the population.

The GACVS concluded that these data support WHO’s statement that inadvertent vaccination of women just before conception or during pregnancy poses little, if any, risk to the developing fetus. However, foetal infections have been documented and, although they have not been associated with congenital rubella syndrome, as a precautionary measure rubella vaccination should still be avoided in pregnancy.