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Safety data from 4 randomized controlled trials (310 pregnancy outcomes), 1 prospective observational study (546 pregnancy outcomes), 5 retrospective observational studies (124,810 pregnancy outcomes), all conducted in pregnant women, and from passive surveillance of women who received ADACEL or ADACEL-POLIO (Tdap-IPV; containing the same amounts of tetanus, diphtheria and pertussis antigen as ADACEL) have shown no vaccine-related adverse effect on pregnancy or on the health of the fetus/newborn child. No unexpected adverse events were observed following vaccination of pregnant women with Adacel. The most common adverse events were injection site reactions. The adverse event profile for Adacel in pregnancy is similar to the profile when given to non-pregnant women (see ADVERSE REACTIONS). As with other inactivated vaccines, it is not expected that vaccination with ADACEL during any trimester would harm the fetus.
Although some observational studies report a slight increase in chorioamnionitis when Tdap vaccine has been given to pregnant women, this has not been associated with adverse outcomes for the pregnant women or their newborns. The causal association between Tdap vaccine and chorioamnionitis has not been established.
Animal studies do not indicate direct or indirect harmful effects with respect to pregnancy, embryonal/fetal development, parturition or postnatal development.
Limited clinical data have shown there is interference with the immune response to other antigens (i.e. diphtheria, tetanus, polio, pneumococcal, meningococcal) in infants born to women vaccinated with ADACEL during pregnancy. However, in most of the cases, the antibody concentrations remain above the thresholds established as protective. The clinical relevance of this observation is unknown.
Passive protection of neonates and infants against pertussis: Based on findings from multiple studies of ADACEL and ADACEL-POLIO administered to pregnant women: Pertussis antibody responses in pregnant women are generally similar to those in non-pregnant women; Maternal antibody directed against pertussis antigens persists for 2 to 4 months after birth and may be associated with blunting of the infant immune response to active immunization against pertussis (see General under PRECAUTIONS); The effectiveness of maternal immunization against pertussis in the first 3 months of life has been estimated to be >90%. (See Table 2.)
Click on icon to see table/diagram/imageNursing Women: The effect of administration of ADACEL during lactation has not been assessed. As ADACEL is inactivated, any risk to the mother or the infant is improbable. However, the effect on breast-fed infants of the administration of ADACEL to their mothers has not been studied. The risks and benefits of vaccination should be assessed before making the decision to immunize a nursing woman.
