Vaccine, Varicella Virus in Pregnancy and Breastfeeding

Risk Factor: CM
Class: Serums, toxoids, and vaccines / Vaccines

Contents of this page:
Fetal Risk Summary
Breast Feeding Summary
Questions and Answers

Fetal Risk Summary

Varicella virus vaccine is prepared from the Oka/Merck strain of live, attenuated varicella-zoster virus (1,2). The vaccine became commercially available in May 1995. Animal reproductive studies have not been conducted with the vaccine.

The manufacturer considers vaccination of a woman within 3 months of conception and during pregnancy to be contraindicated because the effects of the vaccine on the fetus are unknown (1). Both the Advisory Committee on Immunization Practices (ACIP) and the American Academy of Pediatrics, however, recommend avoiding pregnancy for only 1 month following an immunization injection (2,3). Furthermore, vaccination of a child is not contraindicated if the child's nonimmune mother or other nonimmune household member is pregnant (2,3).

A large number of References have described the effects of natural (wild) varicella infection during pregnancy on the fetus and newborn (3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25, 26,27,28,29,30,31,32,33,34,35,36,37,38 and 39). Infection with wild varicella zoster virus during the first 20 weeks of pregnancy is associated with a risk of congenital varicella syndrome (2,4,5 and 6). The syndrome is commonly characterized by low birth weight. Other clinical features, not all of which may be apparent in each case, are shown below (2,4,5 and 6): Cutaneous: cicatricial skin lesions, denuded skin Neurologic: microcephaly, cortical atrophy, myoclonic seizures, hypotonia, hyporeflexia, encephalomyelitis, dorsal radiculitis, Horner's syndrome, bulbar dysphagia, deafness, mental retardation Ophthalmic: microphthalmia, chorioretinitis, cataracts, nystagmus, anisocoria, enophthalmos, hypoplasia of the optic discs, optic atrophy, squint Skeletal: limb hypoplasia of bone and muscle (usually on same side as scarring), hypoplasia of mandible, clavicle, scapula, ribs, fingers and toes, club foot Gastrointestinal: gastroesophageal reflux, duodenal stenosis, jejunal dilatation, microcolon, atresia of sigmoid colon, malfunction of anal sphincter Genitourinary: neurogenic bladder In addition, infection in the 2nd and 3rd trimesters (13 weeks' gestation to term) is associated with a risk of clinical varicella infection during the newborn period or with clinical zoster during infancy and early childhood (2). Severe neonatal varicella may occur in 17%30% of newborns if the onset of maternal varicella infection is 5 days before to 2 days after delivery (2). Although based on small numbers, possibly affected by reporting bias and not reflective of modern treatment models (data reported in 1974), the death rate in neonates whose mothers had an onset of rash 04 days before delivery was 31% (2).

Data from five prospective studies indicate the risk of congenital varicella syndrome during the 1st trimester was 1.0% (6 of 617 infants) (range 0%9.1%) (4,7,8,9 and 10). A higher risk, 2.0% (7 of 351 infants), was found if the infection occurred during 1320 weeks' gestation (10). Based on these five studies, the overall incidence of congenital varicella syndrome from maternal infection during the first 20 weeks' gestation was 1.3% (13 of 968).

In addition to children 12 months of age or older who have not had varicella, the ACIP recommends vaccination for nonimmune adults because of the severity of chickenpox in this population (2,3). Vaccination is contraindicated in pregnancy because of the unknown effects of the vaccine on the fetus and because of the known fetal adverse effects of the natural (wild) varicella-zoster virus (1,2 and 3).

A 1996 report from the manufacturer's pregnancy registry for Varivax described seven pregnant women who had received the vaccine between June 1995 and late 1996 (40,41). The women, thought to be nonimmune, had been exposed to varicella and were inadvertently given the vaccine instead of the indicated varicella-zoster immune globulin (see also Immune Globulin, Varicella-Zoster [Human]). Moreover, one of the women received 5 times the recommended dose of the vaccine (40,41) (see outcome below). None of the women had histories of varicella infection, but their immune status prior to the vaccine was not reported. Four of the seven women had a gestational age at vaccination of <20 weeks, and three had pregnancy durations in the range of >20 weeks to 31 weeks. Two women had delivered healthy children but the outcomes of the other five pregnancies were pending at the time of this report.

The fifth annual report from the manufacturer's pregnancy registry covered the period from March 17, 1995, through March 16, 2000 (42). These data, which include the first seven pregnancy exposures discussed above, involved 509 reports of women vaccinated 3 months prior to or at any time during pregnancy. An additional 54 women had due dates after March 16, 2000, and were not included in the analysis. The number of enrolled women included 486 (95%) prospective cases (reported before the outcome was known) and 23 (5%) retrospective exposures (reported after the outcome was known). In 361 of the 509 reports (71%), the timing of vaccine exposure was known: 136 doses (37%) were administered before the last menstrual period (LMP); 172 doses (48%) were given after the LMP but before the first missed menses; 33 doses (9%) were given before the end of the 1st trimester; and 20 doses (6%) were given during the 2nd or 3rd trimester. Among the 486 prospective cases, 89 (18%) were lost to follow-up and 27 (6%) were electively aborted. In the remaining 370 women with known outcomes, there were 42 (11.1%) spontaneous abortions (SABs), 1 (0.3%) late stillbirth, and 327 (88.6%) live births. Among the 23 retrospective reports, there were 6 (26%) SABs, 2 (9%) elective abortions, and 15 (65%) live births. From all reports, 12 congenital anomalies were identified, but the majority of the pregnancies ending in abortion (spontaneous or elective) did not have morphologic and/or chromosomal evaluations. Details of the 12 cases of anomalies with the time of exposure are shown below: Prospective: Full-term live born: postaxial polydactyly; 2 weeks after LMP Full-term live born: tetralogy of Fallot; 2 weeks after LMP Full-term live born: hypospadias; 6 and 3 weeks before LMP Full-term live born: hypospadias, intrauterine growth retardation; 4 weeks after LMP Full-term live born: preauricular sinuses; 10 and 2 weeks before LMP Elective abortion: Trisomy 21 (Down's syndrome); 3 weeks after LMP Elective abortion: Trisomy 18; 3 weeks after LMP Retrospective Preterm live born: left renal dysplasia, right renal hyperplasia, creatinine clearance 70% of normal, delivered at 35 weeks' gestation; 28 weeks after LMP Live born: left orbital roof defect with encephalocele, left anopthalmia, left suprasellar arachnoid cyst, microcephaly, seizure activity, infant had negative antibody test for varicella zoster virus; 4 weeks after LMP SAB: cystic hygroma, anasarca, brachydactyly, single palmarcreases, two-vessel cord, chromosomal analysis un-successful; 11 weeks before LMP Elective abortion: holoprosencephaly, cleft lip and palate, normal male karotype; 11 weeks before LMP Elective abortion: trisomy 21 (Down's syndrome), clinodactyly, possible paternal X-ray treatment for Hodgkin's disease; 9 and 4 weeks before LMP The 1.8% (7 of 397) incidence of anomalies in the prospective group of live-born infants is well within what is expected in a nonexposed population. The greater number of adverse outcomes in the retrospective group most likely reflects reporting bias. One woman who had received 5 times the normal dose of the vaccine delivered normal twin infants. Moreover, none of the known outcomes in either the prospective or retrospective groups had malformations consistent with the congenital varicella syndrome. The two cases of hypospadias were attributed to background incidence and the two cases of Down's syndrome probably reflect the age of the mothers (30 and 40 years). Therefore, although the data do not support a causal relationship between adverse outcomes and the vaccine, there is insufficient statistical power to detect a very low risk for birth defects or cases of congenital varicella syndrome (42).

A 1997 report described a well-documented case of child-to-mother transmission of varicella-vaccine virus (43). A 12-month-old boy received varicella vaccine and about 3 weeks later had approximately 30 generalized lesions without fever or feeling ill. The lesions were thought to be mild varicella. The 30-year-old mother had a serologic titer negative for varicella and a negative urine pregnancy test at that time. Neither the mother nor her child had any evidence (clinical or laboratory) of immunodeficiency. Sixteen days after appearance of the lesions on her child, she developed a papulovesicular rash diagnosed as varicella. A repeat urine pregnancy was now positive with an estimated gestational age of 56 weeks. Five days later, approximately 100 lesions were counted on the mother, who remained afebrile. On repeat test, seroconversion was documented with a positive varicella titer. Virus was isolated from three of the mother's lesions and identified as Oka strain varicella-zoster virus by polymerase chain reaction test, indicating that her lesions resulted from the vaccine administered to her child. She had an elective abortion during the 7th gestational week because of her concerns that the fetus could acquire the congenital varicella syndrome or other malformations. No varicella-zoster virus DNA was isolated from the fetal tissue. The authors, using a transmission rate of 17% reported for vaccinees with leukemia, estimated the risk of virus transmission from a healthy vaccinee with rash to a nonimmune household member to be about 0.85% (43).

In an editorial comment on the above case, the child's medical history before vaccination was thought to be compatible with a significant allergic diathesis (44). Moreover, at the time of the vaccination his eczema was being treated with the topical corticosteroid, desonide 0.05% (44). A combination of factors, including the number of postvaccination lesions on the child, the contribution of the child's eczema to viral expression, the immunosuppression produced by the corticosteroid, the close contact of the mother to the child resulting from the child's age and the application of the topical corticosteroid, and her pregnancy, were believed to account for the abundance of lesions on the mother (44). The author estimated the maximum theoretical risk for congenital varicella syndrome resulting from the transmission of varicella-vaccine virus to a nonimmune pregnant woman to be less than 1 in 10,000 (<0.01%). The actual risk, however, was thought to be exponentially lower, possibly 0, because of the rarity of documented viremia in children after vaccination and the absence of reported embryopathy with attenuated varicella-zoster virus (44). Neither the author of the editorial (44) nor another correspondent (45) thought that vaccination of a child should be postponed if a nonimmune mother was pregnant or attempting to conceive.

In summary, the risk of congenital varicella syndrome with natural (wild) varicella virus is approximately 1%2% during the first 20 weeks of gestation. Moreover, there is significant risk for infectious morbidity and possible mortality in the neonate and young child when maternal varicella infection occurs after the 1st trimester. The risk from the vaccine is thought to be much less because the virulence of the attenuated virus used in the vaccine is less than that of the natural virus. Although varicella virus vaccine is contraindicated immediately before and during pregnancy because of unknown fetal effects, the potential for harmful fetal effects appears to be very low, as estimated above. No cases of varicella vaccine-induced fetal harm have been identified to date. Because of this, the ACIP recommends that a decision to terminate a pregnancy should not be based on whether the vaccine was given during pregnancy (2). Health care professionals are encouraged to report patients who receive the vaccine 3 months before or at any time during pregnancy to the Varivax Pregnancy Registry by calling (800) 986-8999.

Breast Feeding Summary

It is not known whether either the natural (wild) or the attenuated varicella-zoster virus is excreted into breast milk. In a study published in 1986, no viruses were cultured from the breast milk of two women with varicella-zoster virus infections (46). One of the women had a herpes zoster dermatitis 6 months postpartum and was nursing. Direct lesion contact was prevented, and she continued to breast feed. In the other case, the woman developed varicella pneumonia at 40 weeks' gestation and her infant was delivered by emergency cesarean section. The infant did not become infected after prophylactic treatment with immune globulin varicella-zoster (human) and parenteral acyclovir. In spite of the mother's serious postpartum condition, she maintained lactation with a breast pump. Although a varicella virus culture of the milk was negative, the milk was not given to her infant, nor was the infant allowed to breast feed (46).

Both the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics consider the vaccination of a varicella-zoster virussusceptible nursing mother to be appropriate if the risk of exposure to the natural virus is high (2,3).


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Questions and Answers

Varicella Vaccine and Virus?, How does the Varicella vaccine work, like what does it do to the body that makes the body prevent Chickenpox?

And what are the targeted body systems that the varicella affect and what does it do to the affected systems?

Vaccines in general trigger the body's immune system to recognize the target virus. This is done exposing the person to killed or inactivated ("attenuated") virus in some way (often through a shot or drops). The body recognizes a "foreign" substance and creates antibodies to attack and neutralize it. In the future, if the body is again exposed to that virus, it will already know about it and have the ability to attack it in force, usually making the person relatively immune to disease caused by it.

One problem with varicella is that it can lie dormant in the nervous system for many years after a bout of chicken pox, and then reappear as "shingles" (herpes zoster). This is a painful condition in which the skin along the course of nerves in the face and trunk becomes very sensitive; there may be painful eruptions in these locations, as well.

Varicella (chicken pox) vaccine question - contagious?, I've never had chicken pox (varicella), and I've had the chicken pox vaccine *twice* (back in 2003). I've been tested for chicken pox titres before (back in 2002) and even well after having both sets of the vaccine (back in 2005) - I'm still not immune. My 2 year old will be getting the chicken pox vaccine in another month - I understand it is a live attenuated virus vaccine, which basically means that it's the real deal (not killed), but it's been modified to the point where it's not as strong as the "wild" virus What are the chances that I could catch chicken pox from my child who gets this live vaccine? BTW, I'm 34 yrs old. Thanks.

This isn't an unknown phenomenon. Sometimes people just don't respond to the vaccine. (I actually had it when I was 18mths and when I went to nursing school was tested and came back non-immune)

The most contagious area on your child will be the site of the vaccine. S/he may develop a blister on the site of the vaccination. This lesion will be contagious. The best thing you can do is to keep it covered with a bandaid and wear gloves when you change the bandaid out. Make sure it stays covered until it has dried up and looks scabby. Then it won't be contagious anymore. Be really good with your handwashing for yourself and your 2 yo (I know, THAT's a challenge!) to try to prevent spreading it.

You might talk to the doctor about trying one more time with the vaccine. Sometimes it's just that magic number of exposures to the virus that pushes you into immune response. I suggest this only because as you get older, the chickenpox virus affects you more seriously.

I hope that helps. Good luck.

Is the varicella (chickenpox vaccination) contagious towards a 3rd party? Can it give someone else shingles?, My son is due for his 12 month shots today. That includes the varicella vaccine. It supposedly contains a live virus. A girl I know told me that this vaccine that he is about to take may affect his grandfather, who is on kidney dialysis and takes plenty of meds. She said something about it could give him Shingles if I take my son around him. Is this true? What are the risks of this shot towards other individuals?

If he's had chicken pox he's immune to getting chicken pox. If your son gets a rash from the vaccine he'd need to stay away from pregnant women and children who haven't had chicken pox or people with compromised immune systems. Older people get shingles from the virus lying dormant in their body since they had the chicken pox. They don't know why the virus reappears except it seems to do it in older people and people with compromised immune systems. They have a shingles vaccination available now recommended for people over 60.
Here's a link to who shouldn't get it.