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VACCINE SAFETY: IMMUNIZATION DURING PREGNANCY

Sunday, 21st of July 2013

• IMMUNIZATION DURING PREGNANCY

Vaccine-preventable infectious diseases are responsible for significant maternal, neonatal, and young infant morbidity and mortality. Maternal immunization can protect the mother directly against vaccine-preventable infections, and provide a cocooning effect that can potentiallyprotect the fetus. It can also provide further direct fetal/infant protection against infection via the transport of specific antibodies to the fetus prior to birth.

At its meeting in December 2011, the Strategic Advisory Group of Experts (SAGE) asked GACVS to provide supportto the review of current evidence on the safety of vaccinations in pregnant and lactating women. This request related to uncertainties about the safety of vaccination – whether intended or inadvertent – of pregnant women during mass vaccination campaigns. Such evidence would be particularly important in situations where manufacturers do not recommend the vaccination of pregnant women on precautionary grounds.

Given the broad spectrum of vaccines currently available, GACVS prioritized vaccines for review based on 2 key criteria: their potential to reduce morbidity for the pregnant woman and her fetus; and their use (or projected use) in vaccination campaign settings, which have the potential for inadvertent vaccination of pregnant women. GACVS evaluated relevant data from interventional and non-interventional studies and spontaneous reporting systems on the safety of immunization of pregnant women for several viral, bacterial inactivated vaccines, toxoid and live attenuated vaccines.

Based on the reviewed data, GACVS concluded that there is no evidence of adverse pregnancy outcomes from the vaccination of pregnant women with inactivated virus, bacterial, or toxoid vaccine. Therefore, pregnancy should not preclude women from immunization with the assessed vaccines if medically indicated.

Live vaccines may pose a theoretical risk to the fetus. However, there is substantial literature available describing the safety of live attenuated vaccines including monovalent rubella vaccines, combined measlesmumps-rubella vaccines, and oral polio vaccines. No significant adverse effects to the fetus following these live attenuated vaccines have been reported. Thus, the contraindication of measles-mumps-rubella (MMR)-containing vaccines is considered a purely precautionary measure. Inadvertent vaccination of pregnant women with MMR-containing vaccines is not considered an indication for pregnancy termination.

The benefits of vaccinating pregnant women generally outweigh the potential risks of exposure to a particular infection to the mother or her fetus/newborn if the vaccine is unlikely to cause harm. The use of selected vaccines in pregnancy is an important aspect of prenatal care, which not only improves maternal health but also benefits the neonate.