Smallpox Vaccination in Pregnancy: A Prospective Study

Bourke, Geoffrey J.; Whitty, Richard J.

doi:10.1136/bmj.1.5397.1544

Cited by 20 publications

(5 citation statements)

References 6 publications

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“…The other four studies evaluating first-trimester exposure to smallpox vaccination in pregnancy were not associated with a statistically increased risk of congenital defects. 12,21,22,29 No statistical heterogeneity was noted between studies ( I 2 =0.0%, P =.9). The funnel plot and the Harbord test suggest publication bias for this outcome (Harbord P =.045; Fig.…”

Section: Resultsmentioning

confidence: 92%

“…When the five studies restricted to first-trimester smallpox vaccine exposure were analyzed, an association with congenital defects was seen (2.4% compared with 1.5%, pooled RR 1.34, 95% CI 1.02–1.77). 8,12,21,22,29 Overall, the rate of congenital defects ranged from 0.0% to 4.5% among women vaccinated at any time during pregnancy, 0.6–4.5% among women vaccinated in the first trimester, and 0.8–3.7% among unexposed women. In the one study in which first-trimester vaccination was associated with a statistically increased risk of congenital defects (RR 2.60, 95% CI 1.07–6.32), three of the six neonates with congenital defects had clubfoot.…”

Section: Resultsmentioning

confidence: 99%

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Risks Associated With Smallpox Vaccination in Pregnancy

Badell

Meaney‐Delman

Tuuli

et al. 2015

Obstetrics &Amp; Gynecology

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Objective To estimate the maternal and fetal risks of smallpox vaccination during pregnancy. Data Sources MEDLINE, Web of Science, EMBASE, Global Health, ClinicalTrials.gov, and CINHAL from inception to September 2014. Methods of Study Selection We included published articles containing primary data regarding smallpox vaccination during pregnancy that reported maternal or fetal outcomes (spontaneous abortion, congenital defect, stillbirth, preterm birth, or fetal vaccinia). Tabulations, Integration, and Results The primary search yielded 887 articles. After hand-searching, 37 articles were included: 18 articles with fetal outcome data and 19 case reports of fetal vaccinia. Outcomes of smallpox vaccination in 12,201 pregnant women were included. Smallpox vaccination was not associated with an increased risk of spontaneous abortion (pooled relative risk [RR] 1.03, confidence interval [CI] 0.76–1.41), stillbirth (pooled RR 1.03, CI 0.75–1.40), or preterm birth (pooled RR 0.84, CI 0.62–1.15). When vaccination in any trimester was considered, smallpox vaccination was not associated with an increased risk of congenital defects (pooled RR 1.25, CI 0.99–1.56); however, first-trimester exposure was associated with an increased risk of congenital defects (2.4% compared with 1.5%, pooled RR 1.34, CI 1.02–1.77). No cases of fetal vaccinia were reported in the studies examining fetal outcomes; 21 cases of fetal vaccinia were identified in the literature, of which three neonates survived. Conclusion The overall risk associated with maternal smallpox vaccination appears low. No association between smallpox vaccination and spontaneous abortion, preterm birth, or stillbirth was identified. First-trimester vaccination was associated with a small increase in congenital defects, but the effect size was small and based on limited data. Fetal vaccinia appears to be a rare consequence of maternal smallpox vaccination but is associated with a high rate of fetal loss.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Risks Associated With Smallpox Vaccination in Pregnancy

Badell

Meaney‐Delman

Tuuli

et al. 2015

Obstetrics &Amp; Gynecology

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“…Four out of nine studies were considered at critical risk of selection bias for the outcome of spontaneous abortion [24,25,30,31], because participants were selected among women attending participating hospitals or clinics, thus missing those receiving care in different facilities and miscarriages occurring before onset of prenatal care.…”

Section: Discussionmentioning

confidence: 99%

“…Bourke and Whitty (1964) studied 112 women exposed to smallpox vaccine during pregnancy and 448 unexposed mothers attending antenatal clinics in four hospitals in Dublin [24]. The proportion of spontaneous abortion was the same in both groups (OR 1.0; 95% CI 0.11-9.04).…”

Section: Discussionmentioning

confidence: 99%

Safety of Administering Live Vaccines during Pregnancy: A Systematic Review and Meta-Analysis of Pregnancy Outcomes

et al. 2020

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Live-attenuated vaccines (LAV) are currently contraindicated during pregnancy, given uncertain safety records for the mother–infant pair. LAV might, however, play an important role to protect them against serious emerging diseases, such as Ebola and Lassa fever. For this systematic review we searched relevant databases to identify studies published up to November 2019. Controlled observational studies reporting pregnancy outcomes after maternal immunization with LAV were included. The ROBINS-I tool was used to assess risk of bias. Pooled odds ratios (OR) were obtained under a random-effects model. Of 2831 studies identified, fifteen fulfilled inclusion criteria. Smallpox, rubella, poliovirus, yellow fever and dengue vaccines were assessed in these studies. No association was found between vaccination and miscarriage (OR 0.98, 95% CI 0.87–1.10), stillbirth (OR 1.04, 95% CI 0.74–1.48), malformations (OR 1.09, 95% CI 0.98–1.21), prematurity (OR 0.99, 95% CI 0.90–1.08) or neonatal death (OR 1.06, 95% CI 0.68–1.65) overall. However, increased odds of malformations (OR 1.24; 95% CI 1.03–1.49) and miscarriage after first trimester immunization (OR 4.82; 95% CI 2.38–9.77) was found for smallpox vaccine. Thus, we did not find evidence of harm related to LAV other than smallpox with regards to pregnancy outcomes, but quality of evidence was very low. Overall risks appear to be small and have to be balanced against potential benefits for the mother-infant pair.

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“…This could be obviated by periodic revaccination of females as outlined in our article. 2 Our statement that prenatal vaccinia has not yet been reported in the foetus of a woman with a previous history of successful vaccination would not yet appear to have been refuted.-We are, etc., GEOFFREY J. BOURKE. RIcHARD J. WHITTY.…”

Section: Smallpox Vaccination In Pregnancymentioning

confidence: 95%