Varicella Vaccine (Chickenpox)

1. Why get vaccinated?

Chickenpox vaccine is the best way to prevent chickenpox, therefore protecting children and adults from the severe complications and death associated with the disease. Even with uncomplicated chickenpox cases, lost time from school and work and the cost of medications or treatment that may be needed can result in a significant cost for the family.

2. Do children prefer vaccination over having chickenpox?

In a recent study, 7 out of 10 children said given the choice, they’d rather have the shot than have the natural disease. 7 out of 10 children also considered chickenpox to be worse than many other common childhood ailments, including colds, earaches, sore throat, and fever. The study also found that 3 out of 4 parents are unaware that death is a potential complication of chickenpox.

3. How long has chickenpox vaccine been available?

Chickenpox vaccine was licensed by the Food and Drug Administration in 1995 and is now widely available in private doctors’ offices and public health clinics.

4. Who should be vaccinated?

5. Is the chickenpox vaccine required for child care and school entry?

Yes, more than 20 states have passed such requirements - children entering child care and school must have a history of chickenpox, serological (blood) evidence of immunity or evidence of receiving chickenpox vaccine: Many other states are in the process of enacting such requirements.

6. What are the benefits of having chickenpox vaccination requirements for child care and school entry?

The decision to vaccinate an individual child benefits both the individual and the wider community. Having school requirements for vaccination achieves high levels of protection in schools, pre-schools and child care centers resulting in less illness and school time missed by healthy children (some of whom may have serious complications) and less danger of severe infection among children who cannot be vaccinated. Persons who are not able to receive chickenpox vaccine include children with leukemia and other cancers, persons taking high doses of steroid medications for a variety of medical conditions (including asthma), pregnant women and infants less than 1 year of age. These people have a higher risk of developing severe chickenpox with complications. The only way to protect them is to achieve high levels of vaccination coverage among persons in the community so that they are less likely to come in contact with a person with chickenpox.

7. How important is it for adults to be vaccinated for chickenpox?

All adults who have never had chickenpox should be vaccinated. Immunity is especially important for adolescents and adults who have close contact with persons at high risk for serious complications and for those who are likely to come in close contact with children. CDC’s Advisory Committee on Immunization Practices especially recommends vaccination for the following susceptible adolescents and adults:

Adults do NOT need the chickenpox vaccine if:

8. Is the vaccine effective in preventing chickenpox all the time?

No vaccine is 100% effective in preventing disease. For chickenpox vaccine, about 8 to 9 out of every 10 people who are vaccinated are completely protected from chickenpox. The vaccine almost always prevents against severe disease. If a vaccinated person does get chickenpox, it is usually a very mild case with fewer skin lesions (usually less than 50) lasting only a few days, no fever or a low fever, and few other symptoms.

9. I don't think I have had chickenpox, but I am not sure. Is there a blood test available to determine whether or not I have had the disease?

Yes, a blood test is available to check immunity. Since 70% to 90% of adults who do not remember having chickenpox actually have protection in their blood when tested, blood testing before vaccination can be cost saving. Ask your doctor about this blood test. If it is not available, it is still safe to receive the vaccine even if you have previously had chickenpox.

10. Is there anyone who should not receive the chickenpox vaccine?

Yes, certain persons should not receive the chickenpox vaccine. These persons are those who:

If you are not sure, ask your doctor or nurse.

11. What problems can occur after chickenpox vaccination?

12. Have serious reactions ever occurred from the chickenpox vaccine?

As with any vaccine, there is a very small chance that serious problems could occur after getting chickenpox vaccine. However, after distribution of the first 10 million doses of the vaccine, reports of serious adverse events after vaccination for example, seizures, brain infection (encephalitis), pneumonia, loss of balance (ataxia) and severe allergic reactions (anaphylaxis) have been very rare, occurring approximately 1 for every 50,000 doses given. Adverse events that are reported following vaccination may not always be caused by the vaccine. Some may be caused by natural chickenpox virus which is still common in most communities and some may be caused by other viruses that happened to be circulating in the community at the time of vaccination. It is important to note that the risks from the vaccine remain much lower than the risks from the disease.

13. What should I do if there is a serious reaction after chickenpox vaccination?

14. Can the varicella vaccine virus be transmitted (caught from a person who was vaccinated)?

Yes; however, transmission of the varicella vaccine virus is very rare. It has only been documented in healthy persons on three occasions out of the 21 million doses of vaccine distributed. All three cases resulted in mild disease without complication.

15. I recently got vaccinated and then found out I was pregnant. What should I do?

If you discovered that you were pregnant when you got the chickenpox vaccine, or if you get pregnant within 1 month after getting the vaccine, contact your doctor or call (800) 986-8999 (toll-free). The vaccine manufacturer (Merck) and CDC maintain a registry for reports of women inadvertently vaccinated prior to or during pregnancy. There is a theoretical risk that when administered one month prior to, or during, pregnancy, the vaccine may cause birth defects similar to those that can occur from natural chickenpox (for example, limb abnormalities including absence or underdevelopment; abnormal brain development; mental retardation; scarring of the skin; eye abnormalities). So far, there have been no cases reported to the registry of birth defects in babies born to mothers vaccinated during pregnancy similar to those that can occur from having natural chickenpox during pregnancy.

16. My child was vaccinated 2-3 years ago and he/she developed a mild case of chickenpox this year. Why did this happen?

After vaccination, some persons (about 1 person in 10) do not develop enough protection to completely prevent them from developing chickenpox. When they come into close contact with a person with chickenpox, they may develop a mild case of disease with less than 50 spots or bumps. Compared with a case of chickenpox in an unvaccinated child, they will show very little sign of illness and may miss no school or only 1 or 2 days of school. Children who were vaccinated in their early childhood years may have their first close contact with another child with chickenpox in child care or school settings several years after vaccination. This is why they may come down with mild chickenpox several years after they were vaccinated. This form of chickenpox is also called breakthrough disease.

17. Can a vaccinated person who develops a mild case of chickenpox still spread the disease?

Yes. Vaccinated persons who get this milder form of chickenpox may still spread the disease to others who are not protected. Therefore, these individuals should stay at home until the blisters have formed scabs or if there are no blisters present, until no new spots or bumps are forming.

18. If a person who has never had chickenpox or the vaccine comes into close contact with someone with chickenpox, could receiving the vaccine now prevent this person from getting chickenpox?

Yes, varicella vaccination may prevent or modify chickenpox if administered up to 3 days, and possibly 5 days, after a close exposure. Anyone who comes into close contact with a person with chickenpox and has not had chickenpox or the vaccine, should contact their health care provider for vaccination.

19. There have been lots of cases of chickenpox at my child’s school over the past month. Is it too late to have my child vaccinated?

No, it is not too late to vaccinate your child if she/he has not previously had chickenpox or the vaccine. In schools and child care centers, it may take many months for chickenpox to spread to every classroom. At any stage of an outbreak, all susceptible children and adults should be vaccinated.

20. How long does the vaccine protect someone against chickenpox? Will a booster vaccination be needed?

The length of protection/immunity from any new vaccine is never known when it is first introduced. However, available information collected from persons vaccinated in Japan in the United States show that protection has lasted for as long as the vaccinated persons have been followed (25 years in Japan and more than 10 years in the U.S.). Follow up studies to determine how long protection will last and to evaluate the need and timing for booster vaccination, are ongoing. If it is determined in the future that a booster dose is necessary, your health care provider will inform you. Currently, no booster dose is recommended.

21. Have cases of chickenpox declined in the United States since chickenpox vaccine became available?

Yes, cases have declined dramatically. Since 1995, CDC , in collaboration with Los Angeles County, Texas and Philadelphia health departments, has been monitoring chickenpox cases in these 3 areas in the United States. As use of the vaccine has increased, chickenpox cases have declined substantially.