Chickenpox [chik–uh n-poks] is a highly-contagious viral disease that causes an itchy skin rash and blisters. About 33% of people who get chickenpox as children develop shingles as adults.
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Table of Contents for Chickenpox
How many people get chickenpox?
What are the symptoms of chickenpox?
Is chickenpox serious?
What are complications of chickenpox?
How does chickenpox spread?
How long is chickenpox contagious?
How is chickenpox treated?
Can I get chickenpox again?
How effective is the chickenpox vaccine?
Who needs the chickenpox vaccine?
Who should NOT get vaccinated?
What is the immunization schedule for chickenpox?
Is MMRV more dangerous?
Do I need a booster shot?
What type of chickenpox vaccine can I get?
Can I get vaccinated after I am exposed?
Is the vaccine required for school or daycare?
Chickenpox (varicella) is a highly-contagious disease that causes an itchy skin rash and blisters. It is caused by the varicella zoster virus, a member of the herpes family. The disease only occurs in humans. Once infected, the virus remains inactive in the nerves, but it can re-activate later in life and cause shingles (herpes zoster).
Chickenpox is becoming less common. Before widespread childhood vaccination, there were around 4 million cases of chickenpox per year in the U.S., resulting in around 11,000 hospitalizations and 100 to 150 deaths. Vaccination has reduced mortality rates by 90% since 1995.
Chickenpox symptoms usually start 10-21 days after exposure to the virus. This is also considered the incubation period of chickenpox. The illness usually lasts for 5-7 days. It starts with fever, tiredness, poor appetite, or headache for 1-2 days, followed by waves of itchy rashes. Up to 500 red bumps grow all over the face, chest, or back. The bumps look like pimples or bug bites with a small fluid-filled blister. The blisters turn into scabs within 7 days. The rash may spread all over the body — including inside the mouth, eyelids, or genitals.
In healthy children, chickenpox is usually a mild illness that lasts about a week, but there is no way of knowing who will have a serious illness. Infections tend to be more serious in babies under 12 months, teens, adults, pregnant women, and people with weak immune systems.
- Bacterial infections of the skin
- Brain infection or inflammation (meningitis, cerebellar ataxia)
- Bleeding problems
- Bloodstream infection (sepsis)
- Reye’s syndrome
- Encephalitis (1.8 per 10,000 cases)
- Guillain-Barré syndrome
- Hospitalization (2-3 per 1,000 children)
- Death (1 in 40,000-60,000 cases)
The transmission of chickenpox spreads from person-to-person in the air (coughing or sneezing) or direct contact on the skin. You can get chickenpox by touching the fluid of a chickenpox blister or a skin lesion from shingles.
People with chickenpox are contagious for 1-2 days before the rash appears, and until all of the lesions are crusted over. This can take up to 2 weeks. Illnesses last longer in people with weak immune systems.
At-home treatments for chickenpox include calamine lotion and oatmeal baths to help relieve itching. It is a good idea to keep the fingernails trimmed to prevent skin infections from scratching blisters.
DO NOT use aspirin to treat fever in children with chickenpox. This is associated with Reye’s syndrome, a disease of the liver and brain that can cause death.
Antiviral medications (Acyclovir) is a treatment for chickenpox that is
often recommended for people at risk of a serious infection, including:
- People older than 12 years old
- People with chronic skin or lung disease
- People on steroid therapy
- Pregnant women
Yes. Getting chickenpox twice is rare, but it can happen, especially in people with weak immune systems. Exposure to a wild-type chickenpox virus can also lead to re-infection. However, most people only get chickenpox once and have a lifetime immunity.
The chickenpox vaccine was developed in Japan in the 1970s and approved in the United States in March 1995. It is a single-dose injection of a live varicella-zoster virus. The virus causes a mild infection that triggers an immune response. The body fights the virus and creates antibodies against the virus to fight future infections.
Two doses of the chickenpox vaccine are 90% effective at preventing chickenpox. Some people who are vaccinated against chickenpox still get the disease, but it is usually mild with fewer blisters and low fever.
- People who have not had chickenpox
- Healthcare or daycare workers
- College students
- Inmates and prison staff
- Women of childbearing age who are NOT pregnant
- International travelers
- Nursing home residents and staff
- People with a moderate or serious illness: Wait until you recover before you get the vaccine
- Pregnant women: Do not get vaccinated while pregnant. Do not get pregnant until 1 month after the vaccine
- People who are allergic: Do not get vaccinated if you are allergic to a previous dose of the chickenpox vaccine, gelatin, or the antibiotic neomycin
- Cancer: Do not get vaccinated if you have any malignant condition, including blood dyscrasia, leukemia, lymphoma of any type, or other malignant neoplasm affecting the bone marrow or lymphatic system.
- Others: Talk to your doctor if you are taking steroids, have cancer, HIV/AIDS, blood transfusion, or on medication that suppresses your immune system.
Children under 13 years old need two doses of the chickenpox vaccine — the 1st dose at 12-15 months old and a 2nd dose at 4-6 years old. Do not give the MMRV vaccine for the child’s 1st dose. Instead, separate the MMR and chickenpox vaccines.
People 13 years and older who have never had chickenpox or received the vaccine should get two doses at least 28 days apart.
Children who get the MMRV vaccine (ProQuad) between 12-23 months old have a higher risk of a seizure caused by fever (febrile seizure). Instead of MMRV, they should get a separate MMR and chickenpox vaccine. MMRV is not approved for anyone older than 12.
The CDC started recommending a 2nd shot of the chickenpox vaccine in 2006 after studies showed the 1st dose was only 80-85% effective. No one knows how long a vaccinated person is protected against chickenpox. Immunity depends on the strain of the chickenpox virus.
There are two types of chickenpox vaccines in the U.S., which go by the following name(s) — Varivax®, a vaccine only against chickenpox, and ProQuad®, a combination measles, mumps, rubella, and varicella (MMRV) vaccine. ProQuad is not currently on the market. Both vaccines are made by Merck and contain a live attenuated varicella-zoster virus from the Oka strain.
Yes. If you are not immune to chickenpox and you were exposed to someone with the disease, talk to your doctor. You may be able to get the chickenpox vaccine within 3-5 days of being exposed — or a shot of Immune Globulin (IG) to boost your immunity.
As of July 2016, all 50 states and Washington D.C. have state laws requiring 1 or 2 chickenpox immunizations for children entering daycare, elementary school, middle school, and high school. Visit www.Immunize.org/laws for more information on state requirements or chickenpox vaccines.
About 20% of people who get the chicken vaccine develop minor pain, swelling, or redness at the injection site. Less than 5% develop a mild chickenpox-like skin rash up to a month after immunization. About 1 in 10 people develop fever. The risk of severe injury or death is very low.
- Pain, redness, bruising, swelling at the injection site
- Mild chickenpox-like rash
- Runny or stuffy nose
- Feeing tired
- Stomach pain
- Sleep problems
- Joint or muscle pain
- High fever
- Seizure (jerking or staring)
- Severe allergic reaction
- Brain reactions
- Low blood count
- Vision loss or blindness (necrotizing retinitis)
- Interactions with other medications
- Pregnancy complications
- Guillain-Barré syndrome
- Stevens-Johnson Syndrome
- Erythema Multiforme
To learn more about the side effects associated with the chickenpox and/or Varivax vaccine, please visit this page: Chickenpox Vaccine Side Effects
Yes. The chickenpox vaccine contains a live virus. The virus is “attenuated,” meaning it is weaker, but can still potentially cause chickenpox infections in rare cases.