Congenital Yellow Fever Virus Infection after Immunization in Pregnancy

Abstract

To determine whether yellow fever (YF) vaccine administered in pregnancy causes fetal infection, women who were vaccinated during unrecognized pregnancy in a mass campaign in Trinidad were studied retrospectively. Maternal and cord or infant blood were tested for IgM and neutralizing antibodies to YF and dengue viruses. One of 41 infants had IgM and elevated neutralizing antibodies to YF virus, indicating congenital infection. The infant, the first reported case of YF virus infection after immunization in pregnancy, was delivered after an uncomplicated full-term pregnancy and appeared normal. Congenital dengue 1 infection may have occurred in another case. The frequency of fetal infection and adverse events after such exposure could not be estimated; however, the neurotropism of YF virus for the developing nervous system and the now documented possibility of transplacental infection underscores the admonition that YF vaccination in pregnancy should be avoided.

Emerging Role of Zika Virus in Adverse Fetal and Neonatal Outcomes

“…None of these studies indicated that in utero exposure to yellow fever vaccine resulted in an increased risk of major malformations. IgM antibodies against the vaccine strains, however, were detected in cord blood of a newborn, indicating the possibility of intrauterine transmission (245).…”

“…Transmission via breastfeeding has been recorded for the yellow fever vaccine virus (attenuated 17DD substrain; approved by WHO) (244). Several studies have investigated the effect of yellow fever vaccination during early pregnancy (245)(246)(247). None of these studies indicated that in utero exposure to yellow fever vaccine resulted in an increased risk of major malformations.…”

Yellow fever immunizations: Indications and risks

“…A study in Trinidad documented fetal infection in one of 41 infants exposed to maternal vaccination, although no serious congenital anomalies were noted in this or other studies of infants born to women vaccinated during pregnancy [43]. Pregnant women may have a blunted immune response to yellow fever vaccine.…”

Maternal-child health

“…Diagnosis of YFV infection was confirmed in the mother and infant's sera by IgM capture ELISA; and in the infant by RT-PCR. YF vaccine virus has equally been isolated from asymptomatic newborns from pregnant women who were inadvertently administered 17D vaccine strain (Tsai et al, 1993). Transmission of the YFV through breast-feeding has also been recently reported MMWR, 2009;Kuhn et al, 2011).…”