Smallpox vaccine and pregnant women

The last case of naturally occurring smallpox was seen in 1977; in 1980, the World Health Organization (WHO) declared the disease eradicated and recommended that all countries cease vaccinating people against the disease. However, in response to the possibility of smallpox being used as a biological weapon, the U.S. Centers for Disease Control and Prevention (CDC) has developed recommendations for pregnant women.

What risks does smallpox pose to a pregnant women?

Women who develop the disease while pregnant may have a more serious illness and a higher risk of dying than women who are not pregnant. The infection could also cause:¹

• Miscarriage.
• Stillbirth.
• Premature birth.
• The baby to be born with either no problems or smallpox infection.

Before smallpox was eradicated in 1980, infections caused pregnancies to end early in 75% of pregnant women who developed the disease and in 60% of women who developed it later in their pregnancy.¹

What risks does the smallpox vaccine pose to pregnant women?

All people have some risks from the smallpox vaccine. It is made from a live virus called vaccinia. In general, vaccines that contain live viruses are not recommended for use during pregnancy. On rare occasions, smallpox vaccine can cause an infection (fetal vaccinia) in the fetus of a pregnant woman who was vaccinated during her pregnancy, leading to premature delivery, stillbirth, or death of the child soon after delivery. Sometimes a baby who develops fetal vaccinia is born with skin scars but is otherwise healthy. Fewer than 50 cases of fetal vaccinia have ever been reported in the world; three of these cases were in the United States.¹

A woman who has been vaccinated and is considering becoming pregnant should wait until the scab falls off the vaccination site before trying to become pregnant.

Should I get the smallpox vaccine?

In an outbreak, everyone who has been in contact with a person with smallpox or who was exposed to the virus should receive the one-dose vaccine, regardless of age, allergies, pregnancy, or medical conditions.

If you are pregnant and were exposed to smallpox virus, the vaccine would be recommended for you to try to prevent smallpox or to reduce its severity. You should wait to be vaccinated until after you have delivered your baby if you have not been in contact with smallpox virus or a person with it.

What should I do if I am vaccinated and think that I am having a bad reaction?

Call a health professional right away. Tell him or her what is happening, the date and time that it started, and when the vaccination was given. Your health professional will advise you what to do next.

[Adapted from the CDC's Smallpox Vaccination Clinic Guide¹]