Safety of yellow fever vaccination in pregnancy: findings from a cohort of active duty US military women

Abstract

Background Yellow fever (YF) is a rare viral disease that can be prevented through receipt of a live attenuated vaccine. In the US military, service members must receive the YF vaccine before assignment to endemic areas, putting active duty service women at heightened risk for inadvertent exposure during preconception or pregnancy. Few studies have investigated the safety of YF vaccination in pregnancy to date, and none in a military population. Methods Department of Defense Birth and Infant Health Research program data were used to identify pregnancies and infants among active duty US military women, 2003–2014. Multivariable regression models estimated associations with YF vaccine exposure during preconception/pregnancy and adverse outcomes (e.g. spontaneous abortion, birth defects). Sensitivity analyses were performed that excluded pregnancies exposed to other live vaccines. For analyses of birth defects only, a secondary sensitivity analysis was performed that excluded infants diagnosed with chromosomal anomalies. Results Of the 196 802 pregnancies and 160 706 singleton infants identified, 1347 (0.7%) and 1132 (0.7%), respectively, were exposed to the YF vaccine. No increased risks for adverse pregnancy or infant outcomes were observed in the main analysis. In sensitivity analyses that excluded pregnancies exposed to other live vaccines, preconception YF vaccine exposure was associated with birth defects (aRR = 1.71, 95% CI = 1.08–2.73); this association was attenuated when further excluding infants with chromosomal anomalies (aRR = 1.59, 95% CI = 0.97–2.62). Conclusions Overall, YF vaccine exposure did not appear to be associated with most adverse outcomes among this population of pregnant military women. A tenuous association between preconception YF vaccine exposure and birth defects was observed in sensitivity analyses, which may warrant further investigation.

Analysis of the Number and Type of Vaccinations Performed among Polish Soldiers in 2018–2021

“…The vaccine was given to 195,455 women, and then data on the effects of exposure were collected (including problems with conception, premature delivery, low birth weight, birth defects, etc.). The obtained results indicate no harmful effect on the course of pregnancy and the health of newborns in comparison to the unvaccinated population [ 12 ].…”

Vaccination recommendations for pregnant people travelling overseas

“…[14][15][16] Congenital infection appears to occur at a low rate but has never been associated with fetal abnormalities. 16,17 Yellow fever vaccine virus can also be transmitted via breastmilk;…”

“…If travel to an endemic country is unavoidable, pregnant people should consider receiving the vaccine 8 . Many pregnant people have received the yellow fever vaccine with no evidence of adverse outcomes 14–16 . Congenital infection appears to occur at a low rate but has never been associated with fetal abnormalities 16,17 .…”

“…Many pregnant people have received the yellow fever vaccine with no evidence of adverse outcomes 14–16 . Congenital infection appears to occur at a low rate but has never been associated with fetal abnormalities 16,17 . Yellow fever vaccine virus can also be transmitted via breastmilk; in a report where this occurred, the infant developed seizures, required hospitalisation but made a full recovery 18 .…”

Validation of ICD‐9‐CM codes for major genitourinary birth defects in Military Health System administrative data, 2006–2014

“…Such studies are especially relevant among the military population due to unique work‐related exposures. The Department of Defense (DoD) Birth and Infant Health Research (BIHR) program has relied on administrative health data from the Military Health System (MHS) to study risk for genitourinary birth defects among infants born to service members who deployed to hazardous environments (Conlin et al, 2012), and to demonstrate the safety of routine (e.g., influenza and tetanus, diphtheria, and acellular pertussis) and precautionary or contraindicated (e.g., yellow fever, atovaquone‐proguanil) vaccines/agents in pregnancy (Gutman et al, 2019; Hall, Abramovitz, et al, 2020; Hall, Khodr, et al, 2020; Romano et al, 2021). The program additionally reports surveillance estimates to the NBDPN on a biennial basis.…”