Chickenpox Parties: Not Such a Good Idea

Concerns about vaccine safety and fear of the potential side effects of vaccines have led many parents to decide not to immunize their children. Instead, informal networks of parents have been set up to help each other's children catch diseases (such as chickenpox and measles) in what is called "exposure parties". They believe that by exposing children to the viruses they will gain immunity and avoid the vaccine's side effects. This practice is putting many children at risk of developing serious conditions and starting an epidemic.

Thirty years ago, chickenpox parties were common: children would spend the night at the house of a child with chickenpox and be exposed to the disease. Since varicella (chickenpox) is generally a mild disease in childhood (but serious in adolescence and adulthood) and provides lifelong immunity, parents thought chickenpox parties were a good idea.

However, after the varicella vaccine was licensed, children could obtain immunity against varicella without the risks of natural infection and its potential complications.

The varicella vaccine is 85% to 90% effective for prevention of varicella and 100% effective for prevention of moderate or severe disease.

Prior to the approval of the vaccine, there were 3 to 4 million cases of varicella in the United States each year. About 10,000 people were hospitalized with complications, and approximately 100 patients died. While only 5% of reported cases of varicella are in adults, adults account for 35% of the deaths from the disease.

Children receiving varicella vaccine in pre-licensure trials in the United States have been shown to be protected for 11 years; studies in Japan have demonstrated protection for at least 20 years. A new study has shown that the vaccine has been effective during the 8 years following its routine use in the U.S.

Chickenpox parties have made a comeback due in part to the fear that the varicella vaccine might be unsafe. Let's consider the risks of contracting chickenpox against the risks of the vaccine.

Risks of Chickenpox

• Varicella (chickenpox) is an infection caused by the varicella-zoster virus (VZV).
• A child will often get 300 to 500 blisters during the infection, which crust over and fall off in one to two weeks.
• The chickenpox virus can be spread in the fluid from the blisters or droplets from an infected person's nose or throat.
• Varicella is generally a mild disease, but it is highly contagious.
• Varicella and can be severe and even fatal in otherwise healthy children (less than 1 out of every 10,000 cases).
• Chickenpox can cause pneumonia (23 out of every 10,000 cases)
• Chickenpox is an important risk factor for developing severe invasive "strep" (group A streptococcal disease), commonly referred to as "flesh-eating disease." Treatment of this deep infection requires antibiotics and surgery to remove the infected tissue.
• Complications of varicella include bacterial infections (5% of infected children), decreased platelets, arthritis, hepatitis, and brain inflammation (1 in 10,000 cases), which may cause a failure of muscular coordination.
• Complications are more common among adolescents and adults, and in immunocompromised persons of all ages, than in children.
• A woman who contracts chickenpox in early pregnancy can pass the virus to her fetus, causing abnormalities in 2% of cases.

Risks of the Chickenpox Vaccine

• Varicella vaccine is a live attenuated virus vaccine.
• A very mild rash or several small bumps (between 2 and 6) can result in about 1% to 4% of vaccine recipients.
• A majority of people who get the vaccine have no side effects.
• Of those who do have side effects, most will have only a mild reaction such as soreness and swelling where the shot was administered, and a mild rash (occurring about 20% of the time).
• In children, the vaccine does not cause fever.
• There have not been studies comparing fever following vaccination in adults who were vaccinated with adults who were not vaccinated. The vaccine may cause a mild fever 2 weeks after vaccination.
• A seizure (jerking and staring spell) usually caused by fever may occur in less than 1 in 1000 vaccine recipients. This may not be related to the vaccine.
• Children with leukemia get shingles from the vaccine, but at a lower rate than non-vaccinated.
• Immunocompromised children should not receive the vaccine, such as children with leukemia.
  

Balancing the risks of these diseases against the risks of their respective vaccines shows that children are better protected through chickenpox immunization than through chickenpox parties. Furthermore, not immunizing our children could allow long-time controlled diseases to come back to the U.S.