Chicken pox vaccine effectiveness

How Effective Is the Chickenpox Vaccine?

Q1. My 8-year-old woke up with spots on her back, which quickly spread to her chest, stomach, legs, arms, face — seemingly everywhere! She received the chickenpox vaccine when she was a year old. I thought the vaccine was supposed to prevent chickenpox — or at least decrease its severity if a break out did occur.

— Marina, Georgia

You are correct, and you bring up several very important points. The chickenpox vaccine aims to prevent infection. The vaccine is more than 95 percent effective in preventing a severe chickenpox infection. However, 10 to 30 percent of children who have received the vaccine will develop mild chickenpox symptoms after exposure to a person with chickenpox.

People who have been immunized but get an infection are less likely to have high temperatures. They also tend to develop fewer chickenpox “spots,” or vesicles. Those who were immunized but develop an infection get an average of 50 vesicles. Compare that to an average of 250 vesicles in those who develop chickenpox without ever being vaccinated.

Rare complications of the chickenpox virus, also called varicella, include infections in the brain, liver problems, and pneumonia. The vaccine is extremely effective in preventing these rare but serious complications.

The chickenpox vaccine is a very weak version of the chickenpox virus. One possible side effect of the vaccine is a mild form of chickenpox that leads to the appearance of about two to five vesicles.

It is now recommended that most people receive two doses of the varicella vaccine, since not everybody who gets the vaccine produces a strong antibody response after the first vaccination. The vaccine is not recommended for those with a weakened immune system or pregnant women. People who are allergic to components of the vaccine also should not receive it.

New studies show a person’s protection against chickenpox decreases over time. Overall, however, the chickenpox vaccine has dramatically decreased both the number of people who get chickenpox and the severity of the disease, just like you said. Vaccination is strongly recommended by both the American Academy of Pediatrics and the Center for Disease Control.

Q2. On two separate visits, our family practitioner gave my daughter (now 18 months old) vaccinations she had already had. Once it was the polio vaccine, and the other time it was the annual flu booster (the second shot, which children are only supposed to have the first year they get the flu shot). Should I switch doctors? I could see making that kind of mistake once, but two times? We like the doctor otherwise.

To answer your question briefly, I don’t think you should switch doctors if you like the doctor and feel that he or she is smart, keeps current with evidence-based medicine, and has a good bedside manner. I must confess I empathize with your daughter’s physician. The vaccine schedule is very complicated these days and continues to change frequently. In addition, different vaccines are now being grouped in a variety of ways, which further complicates the situation. By 18 months, as I’m sure you are aware, your daughter should have received three polio vaccines; four DTaP (diphtheria, tetanus, and pertussis) vaccines; three hepatitis B vaccines; three or four Haemophilus influenzae vaccines (depending on the brand of vaccine used); four pneumococcal vaccines; one measles, mumps, and rubella vaccine; one varicella (chicken pox) vaccine; one hepatitis A vaccine; and two or three rotavirus vaccines (depending on which brand was used). In addition, it is recommended that your child receive the seasonal influenza vaccine; as you correctly noted, your child is supposed to get two doses of this vaccine the first year she receives it, and one dose annually thereafter.

You can see that, depending on the brands used, the number of vaccines your child should receive can vary. Sometimes medical practices have one brand and then switch to another. In addition, the polio vaccine is often grouped with other vaccines, like DTaP and hepatitis B (called Pediarix), or DTaP and Haemophilus influenzae (called Pentacel). And because of their vaccine supply, some practices may only be able to give you the other necessary vaccines by giving you an additional polio vaccine.

In fact, it is so common for an additional polio vaccine to be given that the American Academy of Pediatrics states on its vaccine schedule that “if 4 doses are given prior to age 4 years, a fifth dose should be administered between 4 through 6 years.”

I don’t know whether your daughter received an extra dose of the seasonal flu vaccine or if she received two of the H1N1 vaccines, as is recommended. The situation can be confusing because it’s recommended that children age 9 and under have two H1N1 vaccines this season, even if they had two seasonal flu shots in an earlier season.

Certainly there are many vaccines these days for kids, which we hope will result in our children being healthier. The additional vaccines you describe should not have adverse effects on your child, and may in fact boost her immune response.

You can help your child get the appropriate vaccines by bringing your child’s vaccine card with you to appointments and reviewing the vaccines with your pediatrician before they’re administered. Many people are concerned about giving their children too many vaccines at one time and stagger their administration, but an unusual schedule can itself lead to an increased risk of vaccine errors.

I am very impressed with your knowledge of the vaccine schedule and commend you. Informed parents can advocate for their children and make sure they get the best health care.

Q3. I have a healthy, energetic 2-and-a-half-year-old. She received immunization shots when she was 2 months old and caught a bad cold right after. For this reason, I decided not to go any further with the immunization, and she has not had any other shots. I know when school starts this will be a problem, but of my three children, she is by far the healthiest. Am I putting her at risk? I would be horrified if something happened to her because of this decision.

— Stacie, California

Many people share your fear of immunizations; however, many studies have shown that vaccinations are a great health benefit to children — more so than any other medical advancement. Diseases that used to cause great harm and even death among children, such as tetanus and diphtheria, almost never occur these days. Meningitis is much less common because of the routine vaccination of children against the bacteria pneumococcus and Haemophilus influenzae. Schools require that children be vaccinated in order to keep the whole community immunized against such diseases. Outbreaks of diseases like measles have occurred in communities where people do not get immunizations.

Although vaccines are tested rigorously, myths about immunizations are plentiful. One very common myth is that vaccines cause autism, but extensive studies on the side effects of vaccines have shown that this claim is unfounded. Your child’s doctor or nurse will inform you of each vaccine’s common side effects. It is important to note that a cold is not a side effect of a vaccine. Children frequently get colds, so the fact that your daughter developed a cold after her two-month-old vaccinations was most likely coincidental.

Although people very rarely experience side effects from vaccines, when they do, the side effects are usually mild, such as a low-grade fever or pain at the site of the shot. The benefits of immunizations outweigh the risks, and I agree with the American Academy of Pediatrics and the Centers for Disease Control and Prevention in recommending that your child, like all healthy children, get vaccinated. There are many diseases that she is still at risk for and should be immunized against: chicken pox, hepatitis B, and tetanus, to name a few.

Q4. My daughter had a second chicken pox vaccination in 2006 when she turned 11. Sometime after the vaccination, I noticed what appeared to be pox marks on her tongue. A year later the marks are still there. Is there any way to clear them up?

— Lenora, Maryland

I would have to have more information about the marks you describe on your daughter’s tongue to give you a specific diagnosis. For instance, I would need to know whether the marks are only on the tongue or also on the gums or the insides of the cheeks. Are the spots painful, do they come and go, and what exactly do they look like? Although children can occasionally get a few pox from the chicken pox vaccine, it is unusual for them to be in the mouth. Actual chicken pox marks may scar the skin, though it is also unusual that they would scar the mouth. The mouth heals incredibly quickly and completely. I am not sure that the marks on your daughter’s tongue were caused by the chicken pox vaccine; the seeming relationship between the marks and the vaccine may just be coincidental.

There are several possible causes of changes in the appearance of the tongue. It could be something called geographic tongue, a benign condition in which the tongue has areas of red surrounded by a whitish edge. This condition is not painful, and the tongue lesions may come and go, often associated with stress. Another possible cause of an unusual appearance of the tongue is enlarged taste buds. Additionally, marks on the tongue may be associated with something else going on in the body.

If the marks on your daughter’s tongue are painful, or if your daughter is experiencing any other symptoms, such as weight loss, I suggest that you take her to her pediatrician to have matters evaluated further.

Q5. A few years ago I had pneumonia. While I was in the hospital, I caught a bacterial infection and was on oral and injected steroids for ten months. I haven’t been myself since then. For example, I have a weak feeling in my legs. Also, I am obese, and every time I try to lose weight, I get sick and have to go on steroids again. I haven’t had any steroids for a year, however. Could the steroids have caused permanent damage to my body? I can’t get any answers.

Steroids are very powerful compounds — they can be lifesaving, but they have the potential to cause significant short- and long-term complications.

Many different classes of steroids are found naturally in the body, but you’ll most commonly hear about a class known as adrenocorticosteroids — substances produced in our adrenal glands.

Science has allowed us to create newer, synthetic versions of these naturally occurring substances. They are often many times more potent — and unfortunately, they carry a greater risk of side effects — than steroids found in our bodies.

These complications can include weight gain, weakness, muscle wasting and inflammation, elevated blood sugar (diabetes), high blood pressure, and increased susceptibility to infections, to name just a few. Long-term use can lead to osteoporosis and bone fractures, as well as significant problems if the steroids are removed from the body too quickly. Your symptoms may indeed be related to your use of steroids, even one year after your last dose. An examination by a physician specializing in muscle disease could help diagnose your problem and develop a plan to deal with your symptoms and their underlying cause. Good luck!

Learn more in the Everyday Health Healthy Living Center.

Chickenpox vaccine overview

The chickenpox vaccine protects against the varicella zoster virus that causes chickenpox.

The chickenpox vaccine is not part of the routine childhood vaccination schedule.

It is currently only offered on the NHS to people who are in close contact with someone who is particularly vulnerable to chickenpox or its complications.

There are 2 chickenpox vaccines currently available. The brand names of the chickenpox vaccine are VARIVAX and VARILRIX.

Read the patient information leaflet (PIL) for VARIVAX.

Read the patient information leaflet (PIL) for VARILRIX.

Who is at risk from chickenpox?

Chickenpox is a common childhood infection. Usually, it’s mild and complications are rare. Almost all children develop immunity to chickenpox after infection, so most only catch it once. The disease can be more severe in adults.

Certain groups of people, however, are at greater risk of serious complications from chickenpox. These include:

  • people who have weakened immune systems through illnesses such as HIV, or treatments like chemotherapy
  • pregnant women – chickenpox can be very serious for an unborn baby when a pregnant woman catches the infection. It can cause a range of serious birth defects, as well as severe disease in the baby when it is born. Read more about what to do if you catch or are exposed to chickenpox in pregnancy

Who should have the chickenpox vaccine?

It is recommended for certain individuals, such as:

  • non-immune healthcare workers
  • people who come into close contact with someone who has a weakened immune system

This is to lower the chances of infecting people at risk. For example, if you’re having chemotherapy treatment, it’s advisable that non-immune children close to you are given the chickenpox vaccine.

The vaccine would also be recommended if you were about to start work in a radiotherapy department and had not had chickenpox before.

How the chickenpox vaccine works

The chickenpox vaccine is a live vaccine and contains a small amount of weakened chickenpox-causing virus.

The vaccine stimulates your immune system to produce antibodies that will help protect against chickenpox.

Read more about live vaccines.

Read more about chickenpox vaccine side effects.

Read more about who should have the chickenpox vaccine.

How is the chickenpox vaccine given?

The vaccine is given as 2 separate injections, usually into the upper arm, 4 to 8 weeks apart.

How effective is the chickenpox vaccine?

It’s been shown that 9 out of 10 children vaccinated with a single dose will develop immunity against chickenpox. Having 2 doses is recommended, as this gives an even better immune response.

The vaccination is not quite as effective after childhood. It’s estimated that three-quarters of teenagers and adults who are vaccinated will become immune to chickenpox.

Read answers to common questions about the chickenpox vaccine.

Chickenpox (Varicella)

Chickenpox used to be very common in the United States. But the good news is that the vaccine has greatly reduced the number of people who get it. Two doses of the chickenpox vaccine are about 94% effective at preventing it. Most people who get the vaccine don’t get chickenpox — and those who do usually get a much milder version of the disease.

There are 2 vaccines that protect against chickenpox:

  • The chickenpox vaccine protects children and adults from chickenpox
  • The MMRV vaccine protects children from measles, mumps, rubella, and chickenpox

Why is the chickenpox vaccine important?

Chickenpox is very contagious — it spreads easily from person to person. And while it’s usually mild, it can cause serious complications like pneumonia (lung infection). Certain people — like infants, people with weakened immune systems, and pregnant women — are at increased risk for complications.

The chickenpox virus can also cause shingles later in life. Shingles is a disease that causes a painful skin rash and can affect the nervous system. Children who get the chickenpox vaccine may have a lower risk of developing shingles later on — and those who do get shingles often have a milder case than someone who has had chickenpox.

Getting vaccinated is the best way to prevent chickenpox. And when enough people get vaccinated against chickenpox, the entire community is less likely to get it. So when you and your family get vaccinated, you help keep yourselves and your community healthy.

Learn more about how vaccines help protect your whole community.

What is chickenpox?

Chickenpox is caused by a virus. Symptoms of chickenpox include:

  • A red, itchy skin rash with blisters
  • Fever
  • Feeling tired
  • Not feeling hungry
  • Headache

Chickenpox usually spreads when a person touches chickenpox or shingles blisters — or if they breathe in the virus. You can breathe in the virus after someone with chickenpox or shingles scratches their blisters, which releases the virus into the air.

It’s also possible to get chickenpox from breathing in tiny droplets from people who have it that get into the air after they breathe or talk. Learn more about chickenpox.

Who needs to get the chickenpox vaccine?

All children, adolescents, and adults who aren’t immune to (protected from) chickenpox need 2 doses of the chickenpox vaccine. People who have only had 1 dose of chickenpox vaccine need to get a second dose.


Children age 12 months and older need to get the chickenpox vaccine as part of their routine vaccine schedule.

See the routine vaccination schedule for infants and children.

Children need 2 doses of the vaccine at the following ages:

  • 12 through 15 months for the first dose
  • 4 through 6 years for the second dose (or sooner as long as it’s 3 months after the first dose)

Children ages 1 through 12 years can get the MMRV vaccine, which is a combination vaccine that protects against chickenpox, measles, mumps, and rubella. Your child’s doctor can recommend the vaccine that’s right for your child.

If your child missed the chickenpox vaccines, talk with your child’s doctor about scheduling a catch-up shot.


If you aren’t immune to chickenpox (if you haven’t had chickenpox in the past or you haven’t been vaccinated against it), you need to get 2 doses of the vaccine about 1 month apart.

Talk with your doctor about how to protect your family from chickenpox.

Who should not get the chickenpox vaccine?

Some people should not get the chickenpox vaccine or may need to wait — for example, if you:

  • Have had a life-threatening allergic reaction to a previous dose of the chickenpox vaccine or any ingredient in the vaccine (including gelatin or the antibiotic neomycin)
  • Have recently had a blood transfusion or were given other blood products (like plasma) in the past 11 months
  • Have an illness that’s more serious than a cold

Be sure to tell your doctor before getting the chickenpox vaccine if you:

  • Have HIV/AIDS or another immune system disorder
  • Are taking medicines that can affect the immune system
  • Are getting treatment for cancer.

What are the side effects of the chickenpox vaccine?

Side effects are usually mild and go away in a few days. They may include:

  • Pain, swelling, and redness where the shot was given
  • Mild rash
  • Low fever

Serious side effects from the chickenpox vaccine are very rare.

Like any medicine, there’s a very small chance that the chickenpox vaccine could cause a serious reaction. Keep in mind that getting the chickenpox vaccine is much safer than getting chickenpox. Learn more about vaccine side effects.

Where can I get more information about the chickenpox vaccine?

Vaccine Information Statements (VISs) have detailed information about recommended vaccines. Read the VISs for vaccines that protect against chickenpox:

  • Chickenpox vaccine
  • MMRV vaccine — protects against chickenpox, measles, mumps, and rubella (for children)

Find the VISs for the vaccines in other languages.

Chickenpox Vaccine Effective For A Long Time

Chickenpox, the childhood infection of earlier generations, has been most recently neutralized by the varicella vaccine – a vaccine that has shown long-term effectiveness against the illness, according to a new study by the Kaiser Permanente Vaccine Study Center.
The study findings, published in the journal Pediatrics, were based on a 14-year study consisting of 7,585 children ranging in age from 12 to 23 months.
The researchers aimed to examine the long-term effectiveness of the vaccine and its influence on the epidemiology of varicella (chickenpox) and herpes zoster (shingles). Additionally, they looked at the results of a second dose of varicella vaccine, which became available in 2006.

Varicella Vaccine Proves Effective Over Time

The varicella vaccine became licensed in the United States in 1995 and was then suggested for regular use to children by the Advisory Committee on Immunization Practices. Before this, chickenpox was prevalent worldwide – with over 90 percent of adolescents becoming infected before the age of 20.
Along the length of the follow-up period, the prevalence rate of chickenpox in this cohort was 9 to 10 times less than the corresponding rates in kids of the same age who were not vaccinated before the vaccine came onto the market.
This means the varicella vaccine has a total effectiveness rate of nearly 90 percent.
Randy Bergen, MD, chief of outpatient pediatrics at Kaiser Permanente’s Walnut Creek Medical Center and a pediatric infectious disease consultant, said:
“Clearly, the vaccine is a very effective tool in preventing or limiting the severity of chicken pox in young people. As with any vaccine, though, the rate of vaccination has a huge impact on effectiveness. The more children vaccinated, the more effective the vaccine is for the entire community. At Kaiser Permanente, our use of a comprehensive electronic health record, Kaiser Permanente HealthConnect®, enables us to quickly identify children in the targeted age ranges who have not been vaccinated, and to reach out to their parents to ensure they get the shots. Keeping vaccination rates high confers benefit on the community as a whole because there are fewer children who can contract and spread the virus.”
Within the study cohort, in the 14 years after the varicella vaccination, there were a total of 1,505 breakthrough cases of chickenpox reported. “Breakthrough cases” are labeled this way because they happen even though a child has gotten the varicella vaccine.
Chickenpox cases were categorized into:

  • mild – less than 50 lesions
  • moderate – 51 to 300 lesions
  • severe – over 300 lesions

Second Dose of Vaccine Even More Effective

Only a few cases were severe, however, prior to the vaccination era, the majority of kids experienced severe symptoms. Prevention of moderate to severe chicken pox was successfully reached after one dose of varicella vaccine – no cases were documented after the second dose.

These vaccines help protect small infants when they come into contact with vaccinated kids, according to previous research by the CDC in 2011.
The prevalence of breakthrough varicella dropped over time, and no rise was seen during the 14 year follow-up period.
The obvious increase in the vaccine’s success over time, according to lead author Roger Baxter, MD, co-director of the Kaiser Permanente Vaccine Study Center, “is likely the result of vaccine failure occurring early, while breakthroughs became rare due to high vaccine effectiveness both directly and through herd immunity.”
The steady decrease in breakthrough rates seen in 2008 and 2009 could have been due to the administration of the second dose in 2006, the researchers suggested. The second dose of varicella is normally administered between ages 4 to 6 years.
However, the researchers point out that if given earlier after the first dose, it could be more beneficial – by giving more protection.
A separate study carried out by Yale University researchers in 2011 showed that double doses of the chickenpox vaccine were found to be more effective than one.
The risk of herpes zoster, frequently known as shingles, was not elevated in vaccinated children and was seen to be reduced in vaccinated children compared with the pre-vaccine era. Among the cohort, there were 46 cases of shingles – showing a nearly 40 percent drop in incidence of herpes zoster in vaccinated children.
In July of 2011, a study from the National Center for Immunization and Respiratory Diseases reported that chickenpox may soon be eradicated in the U.S. Their study showed that deaths from the disease since the vaccine began to circulate have been slim to none.
Written by Kelly Fitzgerald


  • With an inborn error of metabolism at risk of major metabolic decompensation
  • Who are a household contact of a child or adult patient who is immunocompromised or undergoing a procedure leading to immunocompromise, where the household contact has no clinical history of varicella infection or immunisation
  • Vaccine storage and preparation

    Store vaccine and diluent as per cold chain between 2°C to 8°C.


    • Varilrix and the alternate Varivax vaccine (not currently available) are interchangeable within a two dose course of vaccines.
    • Varilrix should be administered by subcutaneous injection only.
    • Varilrix can be administered concurrently with other vaccines, including MMR, Hib and PCV10 or PCV13. Separate syringes and different injection sites should be used.
      • Giving four injections at the same 15 month immunisation visit is safe and avoids parents and children having to make multiple visits. When receiving just one injection, most children become distressed and settle quickly. Increasing the number of injections won’t always mean more distress, and they can still settle quickly. Delaying immunisation could also leave children unprotected from serious diseases for longer.
    • If Varilrix is not given at the same visit as another live injectable vaccine e.g. MMR, a 4 week interval between the two live virus vaccines should be observed.

    Should children and adults have one or two varicella vaccinations?

    Children aged less than 13 years

    • Parents may choose to purchase a second dose of varicella vaccine, which can be administered a minimum of 4 weeks before or after the first dose.
    • Infants who receive theit first varicella vaccine dose when aged under 12 months of age are recommended to have a second varicella vaccination from age 12 months. Maternal antibodies against chickenpox could be present in infants aged under 12 months and affect the infant’s individual response to the vaccination.
    • In all children aged under 13 years, one dose gives good protection, two doses give optimal protection.

    Children aged 13 years or older and adults

    • The standard varicella vaccine schedule is two doses administered a minimum of 4 weeks apart for individuals in this age group receiving varicella vaccine for the first time.

    Special groups aged 9 months or older

    • Two vaccine doses are recommended and funded for infants, children and adults who meet the eligibility criteria for one of the ‘special groups’ described in the Pharmaceutical Schedule.

    Catch-up doses

    All children, and adults up to 50 years of age, as required.

    Vaccine safety

    Varicella vaccine can be given to:

    • A person living with a newborn baby or a pregnant woman or a person who is immune suppressed.

    Immunisation should be postponed in individuals suffering from a fever over 38°C. However, the presence of a minor infection is not a reason to delay immunisation.

    Varicella vaccine should not be given to:

    • Anyone who has a severe weakness of the immune system
    • Anyone who had a severe allergic response (anaphylaxis) to a previous dose of this vaccine or a component of this vaccine.
    • Women who are currently pregnant. Women are advised to delay pregnancy for 4 weeks after receipt of a varicella vaccine dose.
    • People who have received another live injected vaccine within the previous four weeks

    Advice should be sought for the following groups:

    • People known to have a weakened immune system.
    • People receiving high-dose steroid medicine, e.g. prednisone, for more than 14 days. They should wait for at least four weeks after their treatment has finished before receiving the vaccine.
    • People taking antiviral medication, e.g. tablets for cold sores. These should be stopped for 24 hours prior to immunisation and not restarted for 14 days afterwards.
    • Children taking aspirin. Whilst there has been no association between chickenpox immunisation and Reye’s Syndrome, avoidance of aspirin around the time of immunisation and for six weeks afterward is advised as a precaution.
    • People who have received a blood product in the 11 months before immunisation.
    • People expecting to receive a blood product in the two months after immunisation. These should not be given for two months after immunisation unless their use outweighs the benefits of the immunisation.

    It is possible but extremely rare for a person with a vaccinerelated rash to transfer the vaccine virus to another person, only 10 cases have been reported from around 60 million vaccine doses in the U.S. There is no risk of the vaccine virus being transferred to another person if there is no vaccine-related rash.

    Vaccine effectiveness

    For optimal protection (99%) against all chickenpox disease in children aged nine months up to and including 12 years of age a vaccine course of two doses of Varilrix separated by at least four weeks is recommended. However, a single dose of vaccine offered from the age of 12 months can provide 70–90% protection against all chickenpox, and more than 95% will be protected from moderate-severe disease but may still get mild chickenpox (often fewer than 50 lesions).

    Available information suggests that chickenpox vaccinations may decrease the risk of developing shingles later in life compared with having the wild-type disease.

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