Q&A about the Chickenpox Vaccine
Learn the answers to commonly asked questions about the chickenpox vaccine. Click here to learn more about the chickenpox virus.
Should my child get the chickenpox vaccine?
Yes. Chickenpox is more of a nuisance than just an itchy night or spotted child. It’s a miserable week for the whole family. Children lose sleep and miss school; parents lose sleep and miss work. In addition to a fever, a generally unwell feeling and very itchy spots over the whole body, some children develop accompanying bacterial infections, such as pneumonia or ear infections. The occasional child with chickenpox even needs to be hospitalized. And, of course, chickenpox seems to rear its ugly spots at the most inconvenient times, such as the morning you are leaving for that long-awaited family vacation. Then, just as your first child is getting over the chickenpox and the family is returning back to normal, the spots show up on the next child and you’re in for another miserable week. As an added worry, as soon as you see Susie’s spots, you wonder if you had chickenpox as a child, or if you should cancel your visit to the grandparents. The good news is a chickenpox vaccine is available so that this family nuisance is no longer necessary.
Since chickenpox if often just a harmless nuisance, why should children get the vaccine?
Before the chickenpox vaccine (varicella vaccine, or VV) was available, each year in the United States around four million people developed chickenpox, resulting in around 150,000 to 200,000 persons having complicated chickenpox. Around 14,000 persons were hospitalized each year because of these complications, and around 100 reported people have died from the complications of chickenpox. Approximately half of the chickenpox- related deaths occurred in children. In fact, in the U.S., chickenpox is the leading cause of death from a disease preventable by immunizations. Another fact indicating that chickenpox is not the benign disease it’s reputed to be is that around 1 in 80,000 healthy children who get chickenpox die as a result of the disease.
Does the vaccine always prevent chickenpox?
The main purpose of any vaccine is not necessarily to entirely prevent the disease, but rather to prevent the serious or complicated form of the disease. Recent studies have shown VV to be as much as 95 percent effective toward preventing chickenpox and 100 percent effective for preventing severe chickenpox. Even though between one and four percent of vaccinated children can still get chickenpox, these “breakthrough infections” are mild and usually result in only a few days of a low-grade fever and a few spots.
Does the chicken vaccine last? I’m worried that it may wear off and my child will get chickenpox when he’s older.
This is a valid concern of parents – and doctors – when any new vaccine is introduced. In Medicine 101 you learn, “first do no harm.” Without the chickenpox vaccine, around 2 percent of adults older than thirty years of age in the United States are susceptible to chickenpox. We initially worried that by interfering with the natural course of chickenpox in the general population and immunizing only some children would create a situation decades later in which more than two percent of adults would be susceptible to chickenpox.
Most infection disease experts believe that most vaccines should follow an “all or nothing” principle. This means recommending that all children be immunized against chickenpox. If you only immunize some children, you lessen the chance of natural exposure to the chickenpox and therefore increase the child’s chances of getting it as an adult. For this reason, infection disease experts have mathematically concluded that if more than ninety percent of children receive the chickenpox vaccine, there will be fewer adults susceptible to chickenpox than in the pre-vaccine era. This is the principle behind the American Academy of Pediatrics’ recommendation that: The chickenpox vaccine is added to the routine immunization schedule of all children over one year of age, except under rare medical situations.
How long does the immunity last?
Since the VV was licensed for use in the United States in 1995, it is too early in our country to tell the long-term benefits. Yet, pre-licensure clinical trials in the U.S. have indicated protection for at least thirteen years, and studies in Japan have shown protection for at least twenty years.
I remember having this concern with other “live” vaccines (e.g. measles and German measles) when they were first introduced. Yet, studies have shown that immunity to these vaccines is life-long. Worse case scenario is that a VV booster shot may be needed in adolescence or adulthood, although history with the measles vaccines have shown this not to be necessary. (Even though some schools insist on a second MMR injection before school entry, this policy is not because the immunity has worn off, but because in a tiny percentage of children the original vaccination didn’t take).
Is the chickenpox vaccine safe? Can my child get chickenpox from it?
Yes and yes. Before a vaccine can be licensed, it has to be proven to be both safe and effective – and VV is both. Yet, the following reactions have been reported:
- Around 20 percent of persons experience minor pain, redness, and swelling at the injection site.
- Three to five percent of immunized children develop a mild and noncontagious form of chickenpox, consisting of a low-grade fever and a few spots. While most of these rashes occur within two weeks after the injection, these blister-like spots can occur any time between five to 26 days after the immunization. The risk of developing a vaccine-induced herpes zoster infection (shingles) in persons receiving VV has been estimated to be around two per 100,000 cases. However, the risk would be higher in persons who have compromised immune systems.
- Note: The mild case of chickenpox that may occur in a few children that receive the vaccine is not generally contagious.
Why not just let my child be naturally exposed to chickenpox?
Some parents concerned about the safety of the chickenpox vaccine throw “chickenpox parties” to purposely expose their children to chickenpox as toddlers, since it is much less serious at a younger age than in older children and adults. There are two problems with this reasoning:
- As we have mentioned above, chickenpox can be serious in some children, even though it is usually a mild, weeklong nuisance. Some children can get severe complications, such as pneumonia, encephalitis, overwhelming bacterial infections, and there have been around a hundred deaths reported from chickenpox. It is a nuisance and risk that children no longer need to endure.
- Because so many children are now receiving the vaccine as part of their routine immunizations (in the year 2000 approximately sixty percent of children are receiving routine VV immunization), there are fewer children around to “naturally” expose unvaccinated children. So, as VV becomes more widely used, the chance of your child getting chickenpox naturally becomes less.
Could my child simply have a blood test to see if he’s immune to chickenpox before getting the vaccine?
Yes. This alternative approach is wise in teens and adults who have never had chickenpox. Studies show that the great majority of adults who don’t remember ever having had chickenpox actually are immune to the disease. (Yet, those studies were done in the pre- vaccine days when nearly all persons were exposed at some time in their life to chickenpox and developed immunity to the disease without developing noticeable signs and symptoms of chickenpox.) If as a teen or adult you don’t remember ever having had chickenpox, it would be wise to ask your doctor about having a blood test (called a varicella titer) to see if you are immune to the disease. If you aren’t, you should consider getting the VV vaccine. Around 70 to 90 percent of persons over eighteen years of age who don’t remember ever having had chickenpox will be immune, so it is cost-effective to have a varicella titer, which is much less expensive than two doses of the vaccine. Yet, if you don’t want to have the blood test and would rather get the vaccine, there is no increased severity of reactions in already immunized persons.
Is the vaccine given any differently to teenagers and adults?
Yes. Adults and adolescents over thirteen years of age should receive two doses of the vaccine four to eight weeks apart, a regimen which raises the effective rate of the vaccine from 75 percent from one injection to 99 percent after the second injection. If a teen or adult forgets to get the second dose four to eight weeks after the first, it’s not necessary to restart the two-dose series. Getting a second dose at any time after the first one will certainly boost the chances for full immunity.
NOTE: Spare your teen having to get two shots: get your child the VV by age twelve.
Are there any persons who shouldn’t get the chickenpox vaccine?
The varicella vaccine should either not be used or used with caution and careful medical advice in the following situations:
- VV should not be given to persons allergic to any component of the vaccine, such as neomycin and gelatin. The vaccine does not contain preservatives or egg protein, so that egg allergy is not a contraindication to getting the VV.
- Persons with immuno-deficiencies, such as HIV or leukemia.
- Persons taking large doses of cortisone.
- Persons on any medications that lower the immune system.
If my child is vaccinated against chickenpox, can he pass the disease on to other people?
Possibly, but it is very rare. Studies show that after fourteen million doses of VV, only three cases have been reported in which the vaccinated person transmitted chickenpox to another person, and those occurred only if the immunized person developed a rash.
If my child hasn’t had the chickenpox vaccine, or chickenpox, and he’s exposed to someone with chickenpox, should he get the vaccine?
Yes. The vaccine is about 90 percent effective for preventing chickenpox if given within three days after exposure to the person who has chickenpox. Certainly, if the contacts do develop chickenpox after exposure, if they have been immunized the disease is likely to be much less severe.
Is it safe to get the chickenpox vaccine while pregnant?
Possibly. If you are pregnant and want to get the chickenpox vaccine, first ask your doctor to do a blood test (varicella titer), since chances are great that you are already immune, even though you may not remember having had chickenpox. Certainly, if you got the chickenpox vaccine before you knew you were pregnant, don’t be alarmed, since preliminary studies of 300 such cases indicates no harm to the pre-born baby. Two decades of experience with the rubella vaccine inadvertently given to pregnant mothers has shown the same harmless result. Yet, this question still falls in the “too early to tell” category. Until more experiments and studies are available, it would be wise for pregnant mothers not to get the chickenpox vaccine unless advised by your healthcare provider. It is safe for children and adults to get the chickenpox vaccine if they are living in the household with a pregnant woman. It is recommended that chickenpox- susceptible persons living in the same house with a pregnant woman or person with a depressed immune system get the chickenpox vaccine to protect the pregnant woman or the immuno compromised person from the disease. The person vaccinated who develops a vaccine-related rash should avoid unnecessary contact with the pregnant woman (if she has never had chickenpox) and with immuno compromised persons. If the person who gets the chickenpox vaccine develops a rash and is inadvertently in contact with a pregnant woman or immuno compromised person, don’t worry, since it is unlikely that these persons could contact chickenpox.
Can the chickenpox vaccine be given as the same time as other vaccines?
Observe the following recommendations:
- VV can be given at the same time as the MMR. If given separately, it should be given at least thirty days after the MMR shot.
- VV can be given with all of the other routine immunizations: DPT, DtaP, DTPa, OPV, IPV, Hepatitis B, and HIB.
- VV should not be given for at least five months after the administration of immune globulins, varicella immune globulin, or after having a blood-plasma transfusion.
The American Academy of Pediatrics Committee on Infectious Diseases, Varicella Vaccine Update, Pediatrics Vol. 105, 136-141.