Yellow fever vaccination and pregnancy: a four-year prospective study

Abstract

During an outbreak of yellow fever (YF) in Nigeria in 1986-1987, women at various stages of pregnancy were vaccinated against YF, either because those pregnancies were not known at the time or because they requested vaccination out of fear of acquiring the disease. This offered an opportunity to assess the safety and efficacy of YF vaccine in pregnant women and the effect of this vaccine on their newborn children. Pre-vaccination and post-vaccination serum samples from the vaccinated pregnant women were tested by enzyme-linked immunosorbent assay and by neutralization tests for antibody to YF virus. The results showed that the antibody responses of these pregnant women were much lower than those of YF-vaccinated, non-pregnant women in a comparable control group. Follow-up of these women and their newborn children for 3-4 years showed no abnormal effect that could be attributed to the YF vaccine, which suggests that vaccination of pregnant women, particularly during a YF epidemic, may not be contraindicated.

Efficacy and Duration of Immunity after Yellow Fever Vaccination: Systematic Review on the Need for a Booster Every 10 Years

“…In contrast, a study conducted in Nigeria found that pregnant women had significantly lower levels of neutralizing antibodies than nonpregnant women of childbearing age, male students, and the general population. 56 Only 38.6% had neutralizing antibodies compared with 81.5-93.7% of the other groups. In this study, 88% of immunizations had taken place during the third trimester.…”

“…Only two studies addressed the immunogenicity of YF vaccine in pregnant women. 32,56 These studies reported contrasting results; they showed high seroconversion rates in women vaccinated early in their pregnancy versus low seropositivity after vaccination in their third trimester.…”

“…In this study, 88% of immunizations had taken place during the third trimester. 56 No evidence was found regarding duration of immunity in women who were pregnant at the time of vaccination.…”

Current assessment of yellow fever and yellow fever vaccine

“…Pregnant women may present an immunocompromised profile, which could impair immune responses to YF vaccine. In a study by Nasidi et al [52] from 1993, only one third of approximately 100 pregnant women vaccinated with 17D developed neutralizing antibodies. No adverse effect attributable to vaccination was observed in the pregnant women and fetuses or neonates.…”

Yellow fever immunizations: Indications and risks

“…Pregnant women may have a blunted immune response to yellow fever vaccine. In a study in Nigeria, only 39% of 101 women immunized during pregnancy seroconverted [44]. Women administered the vaccine during pregnancy should be tested for immunity or revaccinated after the pregnancy if they will continue to be at risk for exposure.…”