Vaccine
PREGNANCY RECOMMENDATION: Human Data Suggest Risk
BREASTFEEDING RECOMMENDATION: Contraindicated
PREGNANCY SUMMARY
The CDC classifies smallpox vaccine as contraindicated during pregnancy, within 28 days of conception, and in persons who might have close contact with pregnant women within 28 days of their vaccination (1,2). Other sources also consider smallpox vaccine to be contraindicated during pregnancy (3–6). However, the vaccine should be given to pregnant women who have been exposed to smallpox or monkeypox (1,2,7). Because the risk for fetal vaccinia is low, inadvertent exposure to the vaccine during or before pregnancy should not be a reason for pregnancy termination (1).
FETAL RISK SUMMARY
Smallpox vaccine is a live, attenuated virus vaccine (3,4). Although smallpox infection had a high mortality rate, the disease has been largely eradicated from the world (3,5). Vaccination during pregnancy between 3 and 24 weeks has resulted in fetal death (4,5). A 1974 reference reviewed the published reports of smallpox vaccination during pregnancy and found 20 cases of fetal vaccinia among more than 8500 maternal vaccinations (8). Of the 21 exposed fetuses (1 set of twins), only 3 of the 10 liveborns survived. There was only weak evidence, however, that vaccination during the 1st trimester increased fetal wastage compared with that occurring later in gestation (8).
In a 2004 review that documented the rarity of fetal vaccinia, only about 50 cases were found of fetal infection after smallpox vaccination during pregnancy or shortly before conception (9). Although the exact number of women given the vaccine during pregnancy was unknown, the number is probably large because, in past years, pregnant women were routinely vaccinated during outbreaks of smallpox. The 50 cases were documented in women who had received the vaccine at anytime in pregnancy, after primary vaccination and revaccination, and in nonvaccinated women who had contact with vaccines. The authors concluded that there was insufficient evidence to recommend prophylactic treatment with vaccinia immune globulin if the woman was pregnant or shortly before conception when she received the vaccine (9).
The CDC announced the establishment of the National Smallpox Vaccine in Pregnancy Registry in 2003 (10). The Registry was established to monitor pregnancy outcomes of women who had received the vaccine during pregnancy, or who became pregnant or were in close contact with a vaccinee within 28 days after vaccination. Health care providers and public health staff were encouraged to report cases by calling 877-554-4625 or 404-639-8253 (10).
Two months after the above announcement, the CDC reported, for the period of November 2001–April 2003, that 103 women had received the vaccine either during pregnancy or within 4 weeks of conception (1). The exposures occurred in military personnel, civilian health care and public health workers, and clinical studies. In the civilian group, two women conceived within 1 week before vaccination and four conceived within 28 days after vaccination. Two (timing of vaccination not specified) of the six women had early spontaneous abortions (1). Other pregnancy outcomes, other than these two, have apparently not yet been reported.
BREASTFEEDING SUMMARY
No reports of nursing women receiving smallpox vaccine have been located. In an unusual report, however, tertiary contact vaccinia transmission from a mother to her nursing infant through direct skin-to-skin and skin-to-mucous membrane contact was documented (11). The father, a soldier in the United States Army, had received smallpox vaccination, but had reportedly taken standard precautions to avoid spread to his family. Approximately 1–2 weeks later, his wife developed vesicles on both areolas. About 2 weeks later, a papule developed on the philtrum of the breastfeeding infant. Polymerase chain reaction and culture for vaccinia of the mother and infant confirmed contact vaccinia (11).
Because of the risk of contact vaccinia in a nursing infant, the CDC recommends that breastfeeding mothers should not be routinely vaccinated (11). However, based on the recommendations during pregnancy, if a nursing woman is exposed to smallpox or monkeypox, she should receive the vaccine but should probably stop breastfeeding.
References
1.CDC. Women with smallpox vaccine exposure during pregnancy reported to the National Smallpox Vaccine in Pregnancy Registry—United States, 2003. MMWR 2003;52:386–88.
2.CDC. Guidelines for Vaccinating Pregnant Women. Available at http://www.cdc.gov/vaccines/pubs/preg-guide.htm. Accessed May 16, 2010.
3.Amstey MS. Vaccination in pregnancy. Clin Obstet Gynaecol 1983;10:13–22.
4.American Hospital Formulary Service. Drug Information 1997. Bethesda, MD: American Society of Health-System Pharmacists, 1997:2646–9.
5.Hart RJC. Immunization. Clin Obstet Gynaecol 1981;8:421–30.
6.Linder N, Ohel G. In utero vaccination. Clin Perinatol 1994;21:663–74.
7.Jamieson DJ, Cono J, Richards CL, Treadwell TA. The role of the obstetrician-gynecologist in emerging infectious diseases: monkeypox and pregnancy. Obstet Gynecol 2004;103:754–6.
8.Levine MM. Live-virus vaccines in pregnancy. Risks and recommendations. Lancet 1974;2:34–8.
9.Napolitano PG, Ryan MAK, Grabenstein JD. Pregnancy discovered after smallpox vaccination: is vaccinia immune globulin appropriate? Am J Obstet Gynecol 2004;191:1863–7.
10.CDC. Notice to readers: National Smallpox Vaccine in Pregnancy Registry. MMWR 2003;52:256.
11.Garde V, Harper D, Fairchok MP. Tertiary contact vaccinia in a breastfeeding infant. JAMA 2004;291:725–7.