should a woman wait to become pregnant after receiving varicella
The ACIP and the AAP recommend that a woman not become pregnant for at
least one month following each dose of the vaccine. This differs from the
package insert, which recommends a three month delay.
What is congenital varicella syndrome?
Fetal infection after maternal varicella in the first or early second
trimester of pregnancy may result in varicella
embryopathy, characterized by
limb atrophy and scarring of the skin of the extremity, known as congenital
varicella syndrome. Other manifestations include central nervous system and
What is the risk of congenital varicella syndrome?
Data from a prospective study of 1700 women who contracted varicella
during pregnancy has provided the following risks of congenital varicella
syndrome: 0.4% for infection from 0 to 12 weeks of pregnancy and 2.0% for
infection from 13 to 20 weeks of pregnancy.
- If a woman receives varicella vaccine and subsequently finds out that she
is pregnant, what should she be told about the risk to the fetus?
Since the risk of congenital
varicella syndrome following
natural infection is 0.4-2.0%,
the risk of congenital anomalies
following vaccination with attenuated
varicella vaccine is likely to
be lower or absent. In order
to clarify this risk, Merck and
Co., Inc., in collaboration with
CDC, has established a Varicella
Vaccine in Pregnancy Registry,
similar to that which was established
for rubella vaccine during pregnancy.
So far, there have been no cases
of congenital varicella syndrome
reported to the registry however
the number of women followed
so far precludes excluding a
very low risk. We encourage enrollment
of women who were given varicella
vaccine inadvertently during
pregnancy. Women may be enrolled
in the registry by calling 1-800-986-8999.
For more information on the VARIVAX Pregnancy Registry, visit the
- Shouldchildren and susceptible persons living
in a household with a susceptible pregnant woman be vaccinated ?
Yes, susceptible children
living in a household with a
susceptible pregnant woman should
be vaccinated. Pregnant women
who have never had chickenpox
are at risk of getting chickenpox
during pregnancy. A small percentage
of women who get chickenpox in
the first or second trimester
can have babies with birth defects
known as "congenital varicella
syndrome." In addition,
chickenpox may be more severe
in pregnant women than in others
putting the woman at risk of
severe complications Vaccinating
close contacts of a susceptible
pregnant woman is the most effective
way to protect her from disease.
Although there is a small risk
that a vaccinated person could
get a vaccine rash and spread
the vaccine strain virus to the
pregnant woman, this risk is
much smaller than the risk that
she could contract "natural"
As soon as the pregnant woman delivers her baby, she should be vaccinated
against varicella. The first dose of vaccine can be given before she is
discharged from the hospital and the second dose at the 6-week post-partum
- How should a pregnant woman with varicella be advised and treated?
The woman should be advised that the risk of congenital varicella syndrome is
relatively low (0.4% for infection 1-12 weeks of pregnancy and 2.0% for
infection 13-20 weeks of
pregnancy). The safety of systemic acyclovir therapy among pregnant women has
not been established. Although studies involving animals have not indicated
teratogenic effects of acyclovir, adequate, well-controlled studies among
pregnant women have not been conducted. Acyclovir is classified as Category C in
the FDA use-in-pregnancy rating (i.e., risk cannot be ruled out, but potential
benefits may justify the possible risk) (Burroughs Wellcome Company, Zovirax
package insert). AAP does not recommend oral acyclovir for pregnant women;
however, in instances of serious, viral-mediated complications (e.g.,
pneumonia), AAP states that intravenous acyclovir should be considered.
Burroughs Wellcome Company, in collaboration with CDC and academic
epidemiologists, maintains the Acyclovir in Pregnancy Registry to monitor the
maternal-fetal outcomes of pregnant women who have received systemic acyclovir.
Physicians are encouraged to register pregnant patients who are being treated
with acyclovir by calling (800) 722-9292, ext. 58465.