Chickenpox Vaccine

Chickenpox (also called varicella) is a very contagious disease caused by the varicella-zoster virus (VZV). The U.S. Food and Drug Administration (FDA) approved a live virus vaccine called Varivax in 1995 to prevent chickenpox. The FDA approved a second type of chickenpox vaccine called ProQuad in 2005. Also known as MMRV, ProQuad contains a combination of measles, mumps, rubella and varicella vaccines. Merck & Co. Inc. manufactures both vaccines.

Measles, Mumps, Rubella and Varicella Virus Vaccine Box
Chickenpox Vaccine Facts
  1. Active Ingredients: Varivax-weakened form of chickenpox virus; ProQuad-weakened strains of measles, mumps, rubella and chickenpox viruses
  2. Minimum Age: 12 months
  3. Used to Prevent: Varivax-chickenpox (varicella); ProQuad-measles, mumps, rubella and chickenpox
  4. Manufacturer Merck & Co. Inc.
  5. FDA Approval Varivax approved in 1995; ProQuad approved in 2005

Chickenpox is a common childhood disease that causes a blister-like rash, itching, tiredness and fever. It is spread from person to person through the air or by contact with fluid from chickenpox blisters. The disease is usually mild, but it can lead to severe skin infection, scars, pneumonia, brain damage or death. Someone who’s had chickenpox can get shingles (a painful rash) years later.

Most people who get the chickenpox vaccine won’t get chickenpox, but if a vaccinated person does get chickenpox, he or she usually recovers faster, has fewer blisters and is less likely to have a fever, according to the Centers for Disease Control and Prevention (CDC).

Before the chickenpox vaccine, about 11,000 people were hospitalized for chickenpox annually in the U.S., and about 100 people died from the virus each year. Since the chickenpox vaccine hit the market, the number of outbreaks has gone down, according to the CDC. At least 36 states and the District of Columbia have required children to receive two doses of chickenpox vaccine or have other evidence of immunity against chickenpox before starting school.


Varivax, also known as Varicella Virus Vaccine Live, is given as a shot to people who are 12 months or older. It contains a weakened form a chickenpox as well as gelatin and neomycin. It works by helping the immune system protect a person from getting chickenpox. Varivax may not protect everyone who gets it, and it does not treat chickenpox once a person has the virus. Chickenpox vaccine may be given at the same time as other vaccines.

Small Child with Chickenpox Outbreak
Chickenpox causes a blister-like rash, itching, tiredness and fever

The CDC recommends that children & adolescents and adults get two doses of chickenpox vaccine to prevent the virus. According to the CDC, one dose of a single-antigen varicella vaccine is 85 percent effective at preventing any form of varicella. Getting two doses, on the other hand, is 90 percent effective at preventing any form of varicella. Both one- and two-dose vaccine schedules are 100 percent effective against severe varicella.

Children should get the first dose at 12 through 15 months old and a second dose at 4 through 6 years old, the CDC says. They can get the second dose at an earlier age if it is given at least three months after the first dose.

Anyone who is 13 years of age and older and has never had chickenpox or received the chickenpox vaccine should get two doses at least 28 days apart, the CDC says. The CDC highly recommends chickenpox vaccination for certain people in this category.

The CDC recommends the chickenpox vaccine for:
  • Healthcare professionals
  • Teachers
  • Child care workers
  • Inmates and staff of correctional institutions
  • Non-pregnant women of child-bearing age
  • International travelers
  • People who care for or are around others with weakened immune systems
  • Residents and staff in nursing homes and residential settings
  • College students
  • Military personnel
  • Adolescents and adults living with children

A person should not get Varivax if he or she is allergic to the ingredients in Varivax, which include sucrose, hydrolyzed gelatin, urea, sodium chloride, monosodium L-glutamate, sodium phosphate dibasic, potassium phosphate monobasic, potassium chloride or residual components of MRC-5 cells including DNA and protein, neomycin and bovine calf serum.

It’s usually best to wait to get Varivax if a person is moderately or severely ill at the time the shot is scheduled. Pregnant women should wait to get vaccinated until after they give birth, and women should wait at least one month after getting the chickenpox vaccine to get pregnant. The effects of the vaccine on fetal development are unknown, and it’s not known whether varicella vaccine virus is expelled in human milk, according to the FDA.

Check with a doctor before receiving the chickenpox vaccine if the patient has HIV/AIDS or another disease that affects the immune system, or if the patient has any kind of cancer. Also tell a doctor if the patient is an organ transplant recipient or being treated with drugs that affect the immune system, such as steroids, for two weeks or longer; getting cancer treatment with radiation or drugs; or has recently had a transfusion or was given other blood products.

After getting Varivax, do not take aspirin or aspirin-containing products for six weeks. Though rare, it’s possible to spread the chickenpox virus to others once a patient has gotten the vaccine, so it’s important to try to avoid contact with certain groups of people for up to six weeks after receiving Varivax. These groups include: people who have a weakened immune system; pregnant women who have never had chickenpox; newborn babies whose mothers have never had chickenpox and newborn babies born at less than 28 weeks of pregnancy.

Duration of Varivax Protection

It remains unclear how long the chickenpox vaccine protects a person against the virus; however, live vaccines like Varivax generally provide long-lasting immunity, according to the CDC. Studies conducted before the vaccine was widely used and when chickenpox was still very common in the U.S. showed that people who received the chickenpox vaccine had antibodies for at least one to two decades after vaccination.

One dose of the chickenpox vaccine is 97 percent effective after the first year and 86 percent after the second.

One study that lasted from 1997 to 2003 showed that one dose of the chickenpox vaccine was 97 percent effective and 86 percent effective after vaccination in the first and second years, respectively.

“From the second to eighth year after vaccination, the vaccine effectiveness remained stable at 81 to 86 percent,” according to the CDC. “Most vaccinated children who developed varicella during the eight years after vaccination had mild disease.”

A clinical trial showed that children who received two doses of the chickenpox vaccine were protected for a decade after being vaccinated. Fewer people got chickenpox after two doses compared with one dose, and the risk of getting chickenpox after being vaccinated did not rise over time, according to the CDC.

ProQuad (MMRV)

Unlike Varivax, which is approved for use in children 12 months and older, adolescents and adults, ProQuad is approved only for use in children 12 months through 12 years old. It contains a combination of measles, mumps, rubella (MMR) and varicella vaccines, which is also called MMRV. It may be given as a single shot instead of being administered as the two individual vaccines. Children can get the first dose of MMRV at 12 through 15 months old and a second dose at 4 through 6 years old.

Small Child Getting Shot Injected
Children can get the first dose of MMRV at 12 through 15 months old and a second dose at 4 through 6 years old

ProQuad contains weakened strains of living measles, mumps, rubella and varicella viruses. These strains of live viruses cause either mild or no symptoms of infection. The vaccine works by triggering the body to make disease-fighting antibodies against these infections, thereby producing its own protection. Ideally, if a child is vaccinated with ProQuad, then later comes into contact with measles, mumps, rubella or varicella, the body will produce antibodies to destroy the virus. However, it’s not 100 percent guaranteed that the vaccine will protect all vaccinated children against the viruses. It may take as many as six weeks for full protection to develop. Getting vaccinated before exposure to the viruses is the best protection because it is unclear whether ProQuad will prevent measles, mumps, rubella or chickenpox if received after exposure to the viruses.

Children should not get ProQuad if they have a history of allergic reactions to neomycin or of hypersensitivity to gelatin or any other component of the vaccine or following previous vaccination with ProQuad, Varivax or any measles-, mumps- or rubella-containing vaccine. Children with blood dyscrasias, leukemia, lymphomas of any type or other malignant neoplasms affecting the bone marrow or lymphatic system or who are on immunosuppressive therapy should not get the vaccine either. This is because the chickenpox vaccine can cause a more extensive vaccine-associated rash or disseminated disease in children on immunosuppressive drugs. Other reasons not to get ProQuad include if a child has active untreated tuberculosis or an immunodeficiency, such as HIV/AIDS, or is pregnant.

Reported Chickenpox Vaccine Side Effects

Most people who get chickenpox vaccine do not experience any health reactions as a result. When reactions do occur, they are more likely after the first dose than after the second. The risk of the chickenpox vaccine causing serious harm or death is extremely small; however, like all vaccines, the chickenpox vaccine is capable of causing serious problems, such as severe allergic reactions.

Reactions are more likely to occur after the first dose than the second.

The FDA and the CDC co-manage the Vaccine Adverse Event Reporting System (VAERS), which allows doctors to report when a patient experiences unusual symptoms after getting a vaccine. Between March 1995 and July 1998, VAERS received 6,574 reports of health problems after chickenpox vaccination. About 4 percent of cases were serious including shock, encephalitis (inflamed brain), blood disorder and 14 deaths.

As a result of the adverse event reports documented by VAERS, the FDA added 17 adverse events to Merck’s product label. These include secondary bacterial infections, secondary transmission of vaccine virus infection to close contacts, transverse myelitis (inflammation of the spinal cord), shingles and Guillain-Barré Syndrome (a nervous system disorder).

Adverse effects reported after the chickenpox vaccine include:

Allergic Reactions
  • Anaphylaxis — acute allergic reaction
  • Anaphylactic shock — extreme, life-threatening allergic reaction
  • Angioneurotic edema — rapid swelling of the skin
  • Facial edema — face swelling
  • Peripheral edema — leg swelling caused by fluid in leg tissues
Shoulder Reactions
  • Brachial Neuritis — inflammation of the network of nerves that originate near the neck and shoulder (brachial plexus)
  • Shoulder injury related to vaccine administration (SIRVA)
Eye Reaction
  • Necrotizing retinitis (in immunocompromised individuals) — inflammation of the eye
Blood Reactions
  • Aplastic anemia — the body stops producing enough new blood cells
  • Thrombocytopenia (including idiopathic thrombocytopenic purpura (ITP)) — deficiency of platelets in the blood
Brain Reactions
  • Encephalitis — inflammation of the brain
  • Cerebrovascular accident — stroke
  • Transverse myelitis — inflammation of the spinal cord
  • Ataxia — lack of muscle control or coordination of voluntary movements
  • Aseptic meningitis — inflammation of the lining of the brain
  • Non-febrile seizures — seizure without fever
  • Seizure caused by fever
Nerve and Immune Reactions
  • Guillain-Barré syndrome — body’s immune system attacks the nerves
  • Bell’s palsy — paralysis or weakening of the muscles on the face
  • Paresthesia — burning or prickling sensation often in the hands, arms, legs or feet
Throat and Lung Reactions
  • Pharyngitis — inflammation of the back of the throat
  • Pneumonia — lung infection
  • Pneumonitis — inflammation of lung tissue
Skin Reactions
  • Stevens-Johnson syndrome — life-threatening skin disease
  • Erythema multiforme—skin disorder that presents with bulls-eye-shaped lesions
  • Henoch-Schönlein purpura— inflammation and bleeding in the small blood vessels in the skin
  • Impetigo — highly contagious skin infection that causes sores on the face
  • Cellulitis — potentially serious bacterial skin infection
  • Shingles (herpes zoster) — painful rash caused by reactivation of the chickenpox virus
Other Reactions
  • Soreness or swelling where the shot was given (reported in about one out of five children and up to one out of three adolescents and adults)
  • Fever (reported in one person out of 10, or less)
  • Mild rash up to a month after vaccination (reported in one person out of 25)
  • Dizziness
  • Vasovagal syncope (fainting)
  • Varicella (vaccine strain)

MMRV Vaccine Increased Risks

Children who get the first dose of ProQuad at 12 to 23 months old may have an increased chance of a seizure caused by fever as compared to children who get the MMR and varicella vaccines separately. Known as febrile seizures, these occur in up to 5 percent of toddlers who become feverish for any reason. Such seizures are most common after the MMR or the MMRV vaccine — as many as 300 of each million children vaccinated suffer from febrile seizures.

Seizures caused by a fever usually occur five to 12 days after the first MMRV dose. They typically last no more than two minutes. Fever is reported in about one in 5 people. The first dose of the MMRV vaccine has also been associated with rash. Rash has been reported in about one in 20 people.

What If an Adverse Event Occurs?

If an adverse event occurs after chickenpox vaccination, the most important thing to do is to get medical help immediately. Call 911 or get the person to the nearest hospital if you think he or she is experiencing a severe allergic reaction or another emergency that can’t wait. Otherwise, call the person’s doctor.

After getting medical help, the CDC recommends that the adverse event be reported to VAERS. The vaccinated person’s doctor might file this report, or the patient can report the event through the VAERS website or by calling 1-800-822-7967. VAERS is only for reporting reactions; it does not offer medical advice.

Some people who believe that they or their children were injured by the chickenpox vaccine seek compensation through the National Vaccine Injury Compensation Program (VICP). This federal program was created to compensate people who may have been injured by certain vaccines. To date, the program has paid more than $3 billion to people who have filed petitions. A majority of people choose to enlist the help of a lawyer because this is a legal process.

People injured by the chickenpox vaccine may seek compensation for:
  • Pain and suffering
  • Past lost wages and future loss of earning capacity
  • Any out-of-pocket medical expenses not covered by insurance
  • Future medical care

Please seek the advice of a medical professional before making health care decisions.

Emily Miller
Written By Emily Miller Editor

Emily Miller is an award-winning journalist with 7 years of professional experience writing and editing content for reputable media organizations across the U.S. She also has 13 years of personal experience as a patient living with Crohn’s disease. Her coverage of U.S. prescription drug prices for Drugwatch has been published or cited by news outlets, including The Hill, Fox Business and United Press International. Some of her qualifications include:

  • Society of Professional Journalists and The Alliance of Professional Health Advocates member
  • Centers for Disease Control and Prevention Health Literacy certificates
  • 2016 Florida Society of News Editors third place winner in Breaking News
Edited By
Kevin Connolly
Kevin Connolly Managing Editor
Medically Reviewed By
Dr. John A. Daller
Dr. John A. Daller American Board of Surgery

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