Before the development of the chicken pox, or varicella, vaccine, about 4 million cases of chicken pox occurred annually in the United States. According to the Centers for Disease Control and Prevention, nearly 11,000 people required hospitalization and as many as 150 people died each year due to chicken pox complications. Widespread, routine vaccination against chicken pox has dramatically reduced the incidence of serious illness and death from the virus. While the benefits of the vaccine generally outweigh any possible risks, there are several potentially serious complications from the chicken pox vaccination.
Side Effects
The chicken pox vaccine causes minor side effects in approximately 20 percent of recipients, according to the Centers for Disease Control and Prevention (CDC). In most cases, the side effects are limited to localized pain and swelling at the injection site. As many as 4 percent of recipients develop a rash or a small number of chicken pox-like bumps following vaccination. Serious side effects, such as fever or mild seizures, are rare.
Serious Complications
Some people develop serious, or even life-threatening, complications following chicken pox vaccination. These complications affect an estimated 2.2 out of every 100,000 people and include pneumonia, problems with balance and coordination, encephalitis, severe seizures and anaphylactic allergic reactions. The CDC states that some reported complications from chicken pox vaccination might be due to other viruses or infections.
Infection and Contagion
According to the Immunization Action Coalition, the chicken pox vaccination may cause a mild case of chicken pox in some people. This is because the vaccine is manufactured from a live virus. Transmission of chicken pox following vaccination is also possible, and recently vaccinated persons are encouraged to avoid contact with anyone at risk of chicken pox complications, such as pregnant women and those with compromised immune systems.
Pregnancy and Birth Defects
There is a theoretical risk of infant birth defects occurring because of chicken pox vaccination during pregnancy. Natural chicken pox can potentially cause a host of very serious birth defects in a developing fetus, and the CDC therefore cautions women against undergoing vaccination during pregnancy or in the month prior to becoming pregnant. Possible birth defects and complications include limb abnormalities, mental retardation, skin scarring, abnormal or incomplete brain development and eye problems.
