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Varicella (chickenpox)

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Varicella (chickenpox)

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Varicella (chickenpox)
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Disease Issues
How serious a disease is varicella (chickenpox)?
Prior to the availability of varicella vaccine there were approximately 4 million cases of varicella a year in the U.S. Though usually a mild disease in healthy children, an estimated 150,000 to 200,000 people developed complications, about 11,000 people required hospitalization and 100 people died each year from varicella. Varicella tends to be more severe in adolescents and adults than in young children. The most common complications from varicella include bacterial superinfection of skin lesions, pneumonia, central nervous system involvement, and thrombocytopenia.
How is varicella transmitted and for how long is an infected person contagious?
The varicella zoster virus (VZV) spreads from person to person by direct contact or through the air by coughing or sneezing. It is highly contagious. It can also be spread through direct contact with fluid from a blister of a person infected with varicella, or from direct contact with a skin lesion from a person with zoster (shingles). People with varicella are infectious 1 to 2 days before skin lesions appear until all lesions have crusted over, usually 4 to 7 days after the appearance of skin lesions.
What can be done to protect a patient without evidence of immunity who is exposed to varicella and is at high risk for severe disease and complications?
These patients should receive varicella zoster immune globulin (VariZIG, Saol Therapeutics). VariZIG given up to 10 days after an exposure can modify or prevent clinical varicella disease. See the Varicella Zoster Immune Globulin section below, and www.cdc.gov/mmwr/pdf/wk/mm6228.pdf, pages 574–6). for more information on this topic.
What do you give to a child younger than 1 year of age if they were exposed to the chickenpox or zoster virus?
The minimum age for varicella vaccine is 12 months. Vaccination is not recommended for infants younger than 12 months of age even as post-exposure prophylaxis. CDC recommends that a healthy infant should receive no specific treatment or vaccination after exposure to VZV. The child can be treated with an appropriate antiviral medication if chickenpox occurs.
See the Varicella Zoster Immune Globulin section below for details on the recommended use of VariZIG in immunocompromised children, infants exposed to varicella around the time of birth and some hospitalized preterm infants.
Vaccine Recommendations Back to top
What varicella vaccines are available in the United States?
Two vaccines containing varicella virus are licensed for use in the United States. Both vaccines contain live, attenuated varicella zoster virus (VZV) derived from the Oka strain.
Varivax (VAR, Merck) contains only varicella vaccine virus.
  ProQuad (MMRV, Merck) is a combination measles, mumps, rubella, and varicella vaccine.
Both vaccines are administered by subcutaneous injection. VAR is approved by the Food and Drug Administration (FDA) for people 12 months of age and older. MMRV is approved for people 12 months through 12 years of age. MMRV should not be administered to people age 13 years or older.
Who is recommended to be vaccinated against varicella?
All children, beginning at age 12 months, as well as adults without other evidence of immunity (see next question) should be vaccinated with 2 doses of varicella vaccine. Special consideration should be given to vaccinating adults who (1) have close contact with people at high risk for severe disease (e.g., healthcare workers and family contacts of immunocompromised people), or (2) are at high risk for exposure or transmission (e.g., teachers of young children; child care employees; residents and staff members of institutional settings, including correctional institutions; college students; military personnel; adolescents and adults living in households with children; non-pregnant women of childbearing age; and international travelers).
What are the criteria for evidence of immunity to varicella?
The Advisory Committee on Immunization Practices (ACIP) considers evidence of immunity to varicella to be:
Written documentation of 2 doses of varicella vaccine given no earlier than age 12 months with at least 4 weeks between doses.
  U.S.-born before 1980*
  A healthcare provider's diagnosis of varicella or verification of history of varicella disease
  History of herpes zoster, based on healthcare provider diagnosis
  Laboratory evidence of immunity or laboratory confirmation of disease
    *Note: year of birth is not considered as evidence of immunity for healthcare personnel, immunosuppressed people, and pregnant women.
Does ACIP recommend giving varicella vaccine to infants before age 1 year if they are traveling internationally?
No. ACIP recommends giving a dose of MMR to infants age 6 through 11 months before international travel, but not varicella vaccine. Varicella vaccine is neither approved nor recommended for children younger than age 12 months in any situation.
Can varicella vaccine be used as postexposure prophylaxis for a 9-month-old who was exposed to herpes zoster?
Varicella vaccine is neither approved nor recommended for children younger than age 12 months. Assuming that the child is not immunocompromised, varicella zoster immune globulin (VariZIG) is also not recommended. If the child had a condition which was considered to place the child at greater risk for complications than the general population, then VariZIG could be considered (see the Varicella Zoster Immune Globulin section below and www.cdc.gov/mmwr/pdf/wk/mm6228.pdf, page 574–6).
ACIP does not have a recommendation for acyclovir for varicella postexposure prophylaxis. The American Academy of Pediatrics provide some guidance on this issue in the current edition of the Red Book.
If a healthcare worker does not have a history of varicella vaccination or disease but has had a clinically diagnosed case of shingles, does she or he still need varicella vaccination?
No. A healthcare provider's diagnosis or verification of a history of shingles is acceptable evidence of immunity to varicella. According to ACIP, acceptable evidence of varicella immunity in healthcare personnel includes (1) documentation of 2 doses of varicella vaccine given at least 28 days apart, (2) history of varicella or herpes zoster based on clinician diagnosis, (3) laboratory evidence of immunity, or (4) laboratory confirmation of disease.
I have a patient who is 62 years old and is immigrating to the U.S. She received a dose of live zoster vaccine at age 60. The immigration requirements state she should receive 2 doses of varicella vaccine. Does she need additional varicella vaccine?
To meet the immigration requirements, the dose of live zoster vaccine counts as the first dose of the varicella vaccine series. You should give a dose of varicella vaccine now since it has been more than 4 weeks since the dose of live zoster vaccine. The varicella vaccine dose may not be needed, but it will not be harmful and will allow your patient to meet the regulatory requirement. Note that if the vaccine she received was recombinant zoster vaccine (RZV, Shingrix, GlaxoSmithKline) it does NOT count as the first of two doses of varicella vaccine.
Concerning the recommendation for a second dose of varicella vaccine, does CDC recommend that a teen who received only one varicella vaccine when they were preschool age get a second dose now?
Yes. The current recommendation is for 2 doses regardless of age, for anyone school age and older without evidence of immunity. For everyone whose varicella immunity is based on vaccination, 2 doses of varicella vaccine are recommended.
Originally, ACIP only recommended one dose of varicella vaccine for children. Why did ACIP later revise its recommendations to add a second dose of varicella vaccine for all children?
In the ten years following vaccine licensure in 1995, there was a significant decline in varicella disease, as well as varicella-related hospitalizations and deaths. Although a 1-dose regimen was estimated to be 80% to 85% effective, breakthrough disease was still occurring in highly vaccinated populations. A 2-dose regimen was adopted in 2006 to further reduce the risk of disease among vaccinated people whose numbers would accumulate over time, which could lead to varicella disease later in life when it can be more severe.
Should a child who has had chickenpox prior to the first birthday get the first dose of varicella vaccine at age 1 year?
If the child had confirmed varicella disease or laboratory evidence of prior disease, it is not necessary to vaccinate regardless of age at infection. If there is any doubt that the illness was actually varicella, the child should be vaccinated.
How important is it to vaccinate older children and adults?
It is critical to vaccinate susceptible older children and adults whenever the opportunity arises. With younger children being routinely vaccinated, the chance of being exposed to cases of chickenpox is decreasing. Older children, adolescents, and adults who have not had chickenpox now have a greater chance of remaining susceptible. These older individuals, when they contract chickenpox, are more likely to become seriously ill and have disease complications than younger children.
If an adult or child has not had documented chickenpox but has had shingles, is varicella vaccination recommended?
No. Shingles is caused by varicella zoster virus, the same virus that causes chickenpox. A history of shingles based on a healthcare provider diagnosis is evidence of immunity to chickenpox. A person who has had shingles does not need to be vaccinated against varicella. He/she should still receive zoster vaccine, however, if it is not contraindicated and he/she is age 50 or older.
Can we accept receipt of a single documented dose of live zoster vaccine as proof of varicella immunity in a healthcare employee who has no other evidence of immunity?
No. Receipt of live zoster vaccine is not proof of prior varicella disease. According to CDC, acceptable evidence of varicella immunity in healthcare personnel includes (1) documentation of 2 doses of varicella vaccine given at least 28 days apart, (2) history of varicella or herpes zoster based on clinician diagnosis, (3) laboratory evidence of immunity, or (4) laboratory confirmation of disease. If a healthcare employee has received a dose of live zoster vaccine in the past but has no other evidence of immunity to varicella, the live zoster dose can be considered the  first dose of the 2-dose varicella series. Note that recombinant zoster vaccine (RZV, Shingrix) cannot be counted as the first dose in a 2-dose varicella vaccination series.
Should a person who received 2 doses of varicella vaccine be vaccinated for herpes zoster when they turn 50?
In its 2018 recommendations for the prevention of herpes zoster, ACIP states that Shingrix may be used in adults age 50 years or older irrespective of prior receipt of varicella vaccine or live zoster vaccine (Zostavax, Merck). For details, see www.cdc.gov/mmwr/volumes/67/wr/pdfs/mm6703a5-H.pdf.
If a child has a very mild case of chickenpox (for example, only 5 to 10 pox), is s/he immune or should s/he be vaccinated?
A mild case of chickenpox produces immunity to varicella as does a moderate or severe case. A child with a reliable history of chickenpox does not need to receive varicella vaccine. However, if there is any doubt that the mild illness really was chickenpox, it is best to vaccinate the child. There is no harm in vaccinating a child who is already immune.
I understand that varicella vaccine can be used in postexposure settings. How soon after exposure does the vaccine need to be administered?
Varicella vaccine is effective in preventing chickenpox or reducing the severity of the disease if used within 72 hours (3 days), and possibly up to 5 days after exposure. However, not every exposure to varicella leads to infection, so for future immunity, varicella vaccine should be given, even if more than 5 days have passed since an exposure.
A healthcare worker with no history of chickenpox, and unknown serologic immunity, was exposed to a patient with zoster. She received varicella vaccine two days later. She developed a pruritic maculopapular rash 11 days after vaccination. Is the rash from the vaccine or from her zoster exposure?
The only way to determine whether the rash is caused by wild-type varicella or vaccine virus is to try to isolate virus from the rash and send it to a laboratory that is capable of differentiating wild and vaccine-type virus. This is generally not practical. Given the history, the conservative approach is to assume she has an active case of chickenpox and act according to your infection control guidelines.
Does varicella vaccine affect tuberculosis skin test readings in the same way that MMR does?
There is currently no information on the effect of varicella vaccine on reactivity to a tuberculin skin test (TST). Until information is available, it is prudent to apply the same rules to varicella vaccine as are applied to MMR: a TST (i.e., PPD) may be applied before (preferably) or simultaneously with varicella vaccine. If vaccine has been given, delay the TST for at least 4 weeks.
How has widespread use of varicella vaccine in children impacted disease?
Substantial reductions in varicella morbidity and mortality have occurred following the licensure of vaccine. Reported cases of varicella have fallen more than 95%. For more information on the impact of varicella vaccination see the CDC varicella webpage at www.cdc.gov/chickenpox/surveillance/monitoring-varicella.html.
What are the recommendations for varicella vaccination before and after pregnancy?
Live varicella vaccine should not be given to a woman who is known to be pregnant or who plans to become pregnant within one month. If a woman who is planning to become pregnant in the future comes in for a visit or an annual exam, her varicella history should be obtained and if indicated, 2 doses of vaccine should be given, spaced 4 to 8 weeks apart. Pregnant women should be assessed for evidence of varicella immunity and if non-immune, should receive the first dose of varicella vaccine following completion of the pregnancy and prior to hospital discharge. A second dose should be given 4 to 8 weeks later.
Can a pregnant healthcare worker with a history of varicella infection care for a patient with varicella? Is it possible for her to have a declining titer, thus making her susceptible to the virus again?
People with a reliable history of varicella can be considered to be immune. A reliable history for healthcare personnel consists of (1) a healthcare provider's diagnosis of varicella or verification of history of varicella disease; (2) a history of herpes zoster, based on healthcare provider diagnosis; or (3) laboratory evidence of immunity or laboratory confirmation of disease. Immunity following disease or vaccination is probably life-long. More than one primary infection with varicella is unusual.
Should all pregnant women have serology screening for varicella?
No. Serologic testing for varicella should be considered only for women who do not have evidence of immunity (reliable history of chickenpox or documented vaccination). Once a person has been found to be seropositive, it is not necessary to test again in the future.
If a woman receives varicella vaccine, how long should she wait before becoming pregnant?
Contrary to the information provided in the vaccine package insert, which states that pregnancy should be avoided for 3 months, the ACIP recommends that a wait of 1 month is sufficient.
If a woman receives varicella vaccine and subsequently finds out that she is pregnant, what should she be told about the risk to the fetus?
To date, no adverse outcomes of pregnancy or in a fetus have been reported among women who inadvertently received varicella vaccine shortly before or during pregnancy. The risk of congenital varicella syndrome following varicella disease is small, so the risk of congenital anomalies following vaccination with live attenuated varicella zoster virus (VZV)-containing vaccine is probably very small.
Merck and the Centers for Disease Control and Prevention (CDC) jointly operated a pregnancy registry for women exposed to VZV-containing vaccines for seventeen years after the licensure of varicella vaccine. The registry was discontinued in 2013, having found no signals to indicate a risk of Congenital Varicella Syndrome or pattern of birth defects related to vaccination with VZV-containing vaccines. Healthcare providers may continue to report exposure to VZV-containing vaccines within 3 months of conception or during pregnancy by contacting Merck's call center at 1-877-888-4231.
How has widespread use of varicella vaccine in children impacted disease?
Substantial reductions in varicella morbidity and mortality have occurred following the licensure of vaccine. Reported cases of varicella have fallen more than 95%. For more information on the impact of varicella vaccination see the CDC varicella webpage at www.cdc.gov/chickenpox/surveillance/monitoring-varicella.html.
Scheduling Vaccines Back to top
What is the recommended schedule for vaccinating a child? What about adults?
For children, the first dose should be given at age 12 months with a second dose given at age 4 through 6 years. The second dose could be given earlier, if necessary, as long as there is a 3-month interval between doses. All children age 13 years and older as well as adults without evidence of immunity should also have documentation of 2 doses of varicella vaccine, separated by a minimum interval of 4 weeks.
Some children in my practice have had only 1 dose of varicella vaccine. Is there a problem waiting until the 11- to 12-year-old visit to give them the second dose?
Don't delay giving the second dose of varicella vaccine. Give the second dose the next time the child is in your office. The recommendation to routinely give a second dose at age 4 through 6 years is intended to provide improved protection in the 15% to 20% of children who do not adequately respond to the first dose.
In what circumstances should I obtain a varicella titer after vaccination?
Postvaccination serologic testing is not recommended in any group, including healthcare personnel.
A child received only one dose of varicella vaccine and subsequently tests positive for varicella IgG antibody. Does the child still need a second dose of varicella vaccine?
If a person tests positive for varicella antibody 28 days or more after vaccination, the Advisory Committee on Immunization Practices (ACIP) considers the person to be immune. CDC prefers that the child receive a second dose to assure long-term immunity, but doing so is not absolutely necessary. You can access the ACIP varicella vaccine recommendations, which include evidence of immunity (page 16) at www.cdc.gov/mmwr/pdf/rr/rr5604.pdf.
Should I test women for varicella immunity at their first prenatal visit?
Test pregnant women who lack either (1) documentation of receipt of 2 doses of varicella vaccine or (2) healthcare provider diagnosis or verification of varicella or herpes zoster disease. Women who are not immune should begin the 2-dose vaccination series immediately postpartum.
What is the appropriate lab test to use to determine whether there has been previous chickenpox disease?
Commercially available laboratory tests for varicella antibody are usually based on a technique called EIA (enzyme immunoassay). Though these tests are sufficiently sensitive to detect antibody resulting from varicella zoster virus infection, they are generally not sensitive enough to detect vaccine-induced antibody. The more sensitive assays needed to detect vaccine-induced antibody are not widely available. This is why CDC does not recommend antibody testing after varicella vaccination.
I work in employee health. Several hospital employees have told me they have had chickenpox, but their titers show no antibodies. Should I offer varicella vaccination to them even though they insist they've had the illness?
If you cannot verify a healthcare employee's history of chickenpox, the employee should receive 2 doses of varicella vaccine at least 4 weeks apart. For details, refer to pages 16 and 26 of the CDC recommendations Prevention of Varicella at www.cdc.gov/mmwr/pdf/rr/rr5604.pdf.
A nursing student received 2 valid, documented doses of varicella vaccine. For whatever reason, she subsequently had a titer drawn. The titer was negative. Do you recommend revaccination with 2 doses of varicella vaccine?
No. Documented receipt of 2 doses of varicella vaccine supersedes results of subsequent serologic testing. Most commercially available tests for varicella antibody are not sensitive enough to detect vaccine-induced antibody, which is why CDC does not recommend post-vaccination testing. For more information, see page 24 of ACIP's Immunization of Health-Care Personnel, available at www.cdc.gov/mmwr/pdf/rr/rr6007.pdf.
A child in our practice received her first dose of varicella vaccine when she was 12 months old and her second dose when she was 14 months old. The second dose was only 2 months after the first. Is the second dose valid or does it need to be repeated?
The recommended minimum interval between two doses of varicella vaccine for children 12 months through 12 years of age is 12 weeks. However, the second dose of varicella vaccine does not need to be repeated if it was separated from the first dose by at least 4 weeks. See www.cdc.gov/vaccines/hcp/acip-recs/general-recs/timing.html, Table 3-1.
Contraindications and Precautions Back to top
What are the precautions and contraindications to varicella vaccine?
Recent receipt (within the previous 11 months) of antibody-containing blood product (specific interval depends on product)
  Moderate or severe acute illness with or without fever
  Use of aspirin or aspirin-containing products
  Receipt of specific antiviral drugs (acyclovir, famciclovir, or valacyclovir) 24 hours before vaccination (avoid use of these antiviral drugs for 14 days after vaccination)
history of a serious allergic reaction (e.g., anaphylaxis) after a previous dose of varicella vaccine or to a varicella vaccine component. For information on vaccine components, refer to the manufacturer's package insert (www.immunize.org/fda) or go to www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/B/excipient-table-2.pdf.
  pregnant now or may become pregnant within 1 month
  known severe immunodeficiency (e.g., from hematologic and solid tumors, receipt of chemotherapy, congenital immunodeficiency, long-term immunosuppressive therapy [e.g., two weeks or more of daily receipt of 20 mg or more, or 2 mg/kg body weight or more, of prednisone or equivalent] or patients with HIV infection who are severely immunocompromised [a child age 1 through 5 years with CD4+ T-lymphocyte percentage less than 15% or a person age 6 years or older with a CD4+ T-lymphocyte count less than 200 cells per microliter])
  family history of congenital or hereditary immunodeficiency in first-degree relatives (e.g., parents, siblings) unless the immune competence of the potential vaccine recipient has been clinically substantiated or verified by a laboratory
  for combination MMRV only (approved only for children 1 through 12 years of age), primary or acquired immunodeficiency, including immunosuppression associated with AIDS or other clinical manifestations of HIV infections, cellular immunodeficiency, hypogammaglobulinemia, and dysgammaglobulinemia.
For additional information, see the ACIP General Best Practice Guidelines for Immunization section on contraindications and precautions, table 4–1 and associated footnotes, at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/contraindications.html or consult IAC's "Guide to Contraindications and Precautions to Commonly Used Vaccines" at www.immunize.org/catg.d/p3072a.pdf.
What are the recommendations for the use of varicella vaccine in children with HIV or other immunodeficiencies?
The ACIP General Best Practice Guidelines for Immunization section on altered immunocompetence recommends varicella vaccination of children with humoral (but not cellular) immunodeficiencies. In addition, single-antigen varicella vaccine should be considered for HIV-infected children age 1 through 5 years with CD4+ T-lymphocyte percentages greater than or equal to 15% for at least 6 months or for children age 6 years and older with CD4+ T-lymphocytes count greater than or equal to 200 cells per microliter for at least 6 months. Eligible children should receive 2 doses of varicella vaccine with a 3-month interval between doses. Additional details of these recommendations can be found in table 8-1 and associated footnotes at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/immunocompetence.html.
We have a 40 lb six-year-old patient who has been taking 15 mg of methotrexate weekly for arthritis for 12 months. Can we give the child MMR and varicella vaccine based on this methotrexate dosage?
Based on the weight and dosage provided (40 lbs and 15 mg/week), the child is currently receiving more than 0.4 mg/kg/week of methotrexate. This meets the Infectious Disease Society of America (IDSA) definition of high-level immunosuppression. Administration of both varicella and MMR vaccines are contraindicated until such time as the methotrexate dosage can be reduced. The 2013 IDSA definition of low-level immunosuppression for methotrexate is a dosage of less than 0.4 mg/kg/week. For additional details, see the 2013 IDSA Clinical Practice Guideline for Vaccination of the Immunocompromised Host: cid.oxfordjournals.org/content/early/2013/11/26/cid.cit684.full.pdf.
I had an 18-year-old in the clinic today for varicella vaccination. He reports having antiphospholipid syndrome being treated with rituximab (a drug that affects the function of lymphocytes). The next dose of rituximab will be in 2 weeks. He has also had 12 immune globulin (IG) injections in the last year. Should he get the varicella vaccine at all with this condition, and if so, what time frame do we need to be concerned with in relation to the rituximab treatment and/or IG?
The IDSA guidelines indicate that persons receiving rituximab should be considered to have high-level immunosuppression. Both inactivated and live vaccines should be withheld at least 6 months following treatment with lymphocyte depleting medications such as rituximab. As for the IG, the interval to live vaccination depends on the dose. For guidance, please refer to the Timing and Spacing of Immunobiologics section of the ACIP's General Best Practices Guidelines for Immunization, table 3–5: "Recommended intervals between administration of antibody-containing products and measles- or varicella-containing vaccine, by product and indication for vaccination" at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/timing.html. This interval could be as long as 11 months, depending on the dose he receives.
Recently we had a one-year-old with congenital heart disease and who is on chronic aspirin therapy in for a well-child check and routine vaccination. Are there any recommendations regarding varicella vaccine being given to children who are on chronic aspirin therapy?
The ACIP's varicella vaccine recommendations state that no adverse events associated with the use of salicylates after varicella vaccination have been reported, however, the vaccine manufacturer recommends that vaccine recipients avoid using salicylates for 6 weeks after receiving varicella vaccines because of the association between aspirin use and Reye syndrome after varicella disease (chickenpox). Vaccination with subsequent close monitoring should be considered for children who have rheumatoid arthritis or other conditions requiring therapeutic aspirin. The risk for serious complications associated with aspirin is likely to be greater in children in whom natural varicella develops than it is in children who receive the vaccine containing attenuated varicella zoster virus. In other words, the benefit of varicella vaccine likely outweighs the theoretical risk of Reye syndrome. See the ACIP varicella recommendations at www.cdc.gov/mmwr/PDF/rr/rr5604.pdf, page 29.
After receiving varicella vaccine, should healthcare personnel avoid contact with immunocompromised patients?
This is not necessary unless the person who was vaccinated develops a rash.
Is there any concern when giving varicella vaccine to a child who lives with a susceptible pregnant woman or an immunocompromised individual?
ACIP recommends varicella vaccine for healthy household contacts of pregnant women and immunosuppressed people. Although there may be a small risk of transmission of varicella vaccine virus to household contacts, the risk is much greater that the susceptible child will be infected with wild-type varicella, which could present a more serious threat to household contacts.
A pediatric surgeon's 12-month-old child received the varicella vaccine and two weeks later developed a varicella-like rash. The surgeon had chickenpox as a child and had a positive varicella titer several years ago. Is it okay for the surgeon to continue to see patients? Also, is the varicella virus in the rash that develops following vaccination as virulent as the wild-type virus?
Because the surgeon is immune, the child's rash is not a problem and there is no need for the surgeon to restrict activity. In comparing a vaccine rash to wild-type chickenpox infection, transmission is less likely with a vaccine rash and, in general, there are fewer skin lesions.
If a patient is breast-feeding her six-month-old baby, can she receive varicella vaccine without the risk of transmitting the vaccine virus to her baby?
There has been only one published report of mother to child transmission of varicella vaccine virus. If the susceptible woman were to be infected with wild varicella virus, the risk of transmission to the infant would be much higher. Breastfeeding is not a contraindication or a precaution to varicella vaccination of the mother when vaccination is indicated.
A 10-year-old girl came to our immunization clinic, and the nurse noted crusted lesions on her arms and legs. The parent said the child had had chickenpox a week earlier. The girl was not ill, so we vaccinated her. But now I wonder if her recent case of chickenpox might interfere with her immune response to vaccines.
A previous history of chickenpox disease, even recent disease, is not known to interfere with the immune response to different vaccines. To review the true contraindications and precautions to vaccination, consult IAC's "Guide to Contraindications and Precautions to Commonly Used Vaccines" at www.immunize.org/catg.d/p3072a.pdf.
Another helpful resource is ACIP's General Best Practice Guidelines for Immunization. It contains a useful table titled "Conditions incorrectly perceived as contraindications or precautions to vaccination (i.e., vaccines may be given under these conditions)". The table is available at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/contraindications.html, Table 4-2.
We have a patient who has selective IgA deficiency. We also have patients with selective IgM deficiency. Can MMR or varicella vaccine be administered to these patients?
There is no known risk associated with MMR or varicella vaccination in someone with selective IgA or IgM deficiency. It is possible that the immune response may be weaker, but the vaccines are likely effective.
Vaccine Safety Back to top
How safe is varicella vaccine?
Varicella vaccine is very safe. About 20% of vaccine recipients will have minor injection site complaints, such as pain, swelling, or redness. Fewer than 5% of recipients develop a localized or generalized varicella-like rash 5 to 26 days after vaccination. These rashes have an average of 2 to 5 lesions, and may be maculopapular rather than vesicular. Fever following varicella vaccine is uncommon.
If a child had 1 varicella vaccination and developed a vesicular (chickenpox-like) rash at the vaccination site 7 to 10 days after vaccination, does the patient still need the second dose? What if the rash covered the entire body?
If you believe the child had varicella disease (that is, breakthrough varicella) after the first dose, the child does not need another dose. If you are uncertain whether the child had varicella, the second dose should be administered on schedule. If in doubt, give the second dose. If this was a case of breakthrough varicella, a second dose will not be harmful.
If a child breaks out in 5 to 10 maculopapular spots 2 weeks following varicella vaccination, can s/he go to school?
Transmission of varicella vaccine virus is a rare event, and appears to occur only when the vaccinated person develops a vesicular rash. A maculopapular rash 2 weeks after varicella vaccine may not have been caused by the vaccine. If the rash were caused by the vaccine, the risk of transmission is very small; however, the child should avoid close contact with people who do not have evidence of varicella immunity and who are at high risk of complications of varicella, such as immunocompromised people, until the rash has resolved.
If a vaccinated child gets 5 to 10 vesicular lesions 2 weeks after vaccination, can s/he attend school?
You cannot distinguish a mild case of varicella disease from a rash caused by the vaccine. The child may have been infected with varicella at about the same time s/he was vaccinated. The conservative approach would be to treat the child as if s/he had chickenpox and restrict her/his activities until all the lesions crust.
If a child gets breakthrough varicella infection, about 50 lesions, can s/he go to school?
Breakthrough varicella represents replication of wild varicella virus in a vaccinated person. Although most breakthrough disease is very mild, the child is contagious and activities should be restricted to the same extent as an unvaccinated person with varicella disease.
Can a young child, who was recently vaccinated for chickenpox, spread the vaccine virus to other household members?
Available data suggest that healthy children are unlikely to transmit vaccine virus. Transmission of vaccine virus to a household contact has rarely been documented. It appears that transmission of vaccine occurs mostly, or perhaps even exclusively, when the vaccinated person develops a rash following vaccination.
If a person develops a rash after receiving varicella vaccination, does he need to be isolated from susceptible people who are either pregnant or immunosuppressed?
Transmission of varicella vaccine virus is rare. However, if a pregnant or immunosuppressed household contact of a vaccinated person is known to be susceptible to varicella, and if the vaccinee develops a rash 7 to 21 days following vaccination, it is prudent that they avoid prolonged close contact with the susceptible person until the rash resolves.
An 8-month-old was erroneously given varicella vaccine. What might the consequences be? What should we do now?
An 8-month-old is likely to have residual passive varicella antibody from his or her mother. The vaccine probably will have no effect, and no action is necessary. The dose should not be counted, and the child should be revaccinated on schedule at 12 through 15 months of age.
Varicella Zoster Immune Globulin Back to top
What is varicella zoster immune globulin?
Varicella zoster immune globulin (VariZIG, Saol Therapeutics) is a human blood product prepared from plasma obtained from healthy, volunteer blood donors identified by routine screening to have high antibody titers to varicella-zoster virus. The first varicella zoster immune globulin, VZIG, became available in 1978. In a study of immunocompromised children who were administered VZIG within 96 hours of exposure, approximately one in five exposed children developed clinical varicella, and one in 20 developed subclinical disease compared with 65%—85% attack rates among historical controls. In 2006, VZIG was discontinued and a new product, VariZIG, became available.
In what circumstances should I consider giving VariZIG?
According to CDC the decision to administer VariZIG depends on three factors: 1) whether the patient lacks evidence of immunity to varicella, 2) whether the exposure is likely to result in infection, and 3) whether the patient is at greater risk for varicella complications than the general population. For high-risk patients who have additional exposures to varicella-zoster virus 3 weeks or longer after initial VariZIG administration, another dose of VariZIG should be considered. The most recent recommendations for the use of VariZIG were published in 2013 and are available at www.cdc.gov/mmwr/pdf/wk/mm6228.pdf, pages 574–6.
What groups of patients are eligible for VariZIG?
VariZIG is recommended for patients without evidence of immunity to varicella who are at high risk for severe varicella and complications, who have been exposed to varicella or herpes zoster, and for whom varicella vaccine is contraindicated. Patient groups recommended by CDC to receive VariZIG include the following:
Immunocompromised patients without evidence of immunity
  Newborn infants whose mothers have signs and symptoms of varicella around the time of delivery (i.e., 5 days before to 2 days after)
  Hospitalized preterm infants born at 28 weeks or more of gestation whose mothers do not have evidence of immunity to varicella
  Hospitalized preterm infants born at less than 28 weeks of gestation or who weigh 1,000 grams or less at birth, regardless of their mothers' evidence of immunity to varicella
  Pregnant women without evidence of immunity
CDC recommends administration of VariZIG as soon as possible after exposure to varicella-zoster virus, ideally within 96 hours, up to 10 days after exposure.
What is the recommended dosage of VariZIG?
VariZIG is supplied in 125-IU vials and should be administered intramuscularly as directed by the manufacturer. The recommended dose is 125 IU/10 kg of body weight, up to a maximum of 625 IU (five vials). The minimum dose is 62.5 IU (0.5 vial) for patients weighing 2.0 kg or less and 125 IU (one vial) for patients weighing 2.1–10.0 kg. VariZIG is available from Saol Therapeutics. For ordering information see varizig.com/liquid-product_info.html.
A one-month-old infant was exposed for the last 6 days to chickenpox. What should be done to protect the exposed infant, who is too young to vaccinate?
There is no evidence that healthy full-term infants born to women in whom varicella occurs more than 48 hours after delivery are at increased risk for serious complications such as pneumonia or death. Varicella zoster immune globulin, VariZIG, can be given up to 10 days after exposure but is only recommended for newborn infants whose mothers have signs and symptoms of varicella around the time of delivery (5 days before to 2 days after), hospitalized premature infants born at 28 or more weeks of gestation whose mothers do not have evidence of immunity to varicella, or hospitalized premature infants born at less than 28 weeks of gestation or who weigh 1,000 grams or less at birth regardless of their mothers' evidence of immunity to varicella. Assuming this is an infant at home, VariZIG would not be recommended. Varicella, if it develops, would be managed as for any child.
Storage and Handling Back to top
How should varicella vaccine be stored in my clinic?
Live varicella-containing vaccines (varicella, MMRV) must be stored in a freezer at a temperature between -50°C and -15°C (between -58°F and +5°F) until reconstitution and administration. These vaccines can deteriorate rapidly after they are removed from the freezer. A separate stand-alone freezer should be used to store frozen vaccines that require storage temperatures between -50°C and -15°C (between -58°F and +5°F). A stand-alone storage unit that is frost-free or has an automatic defrost cycle is preferred. Frozen vaccines should not be stored in the freezer compartment of a combination unit because household freezers cannot maintain proper storage temperatures for frozen vaccines. This applies to both temporary and long-term storage of frozen vaccines. The diluents should be kept separately in the refrigerator or at room temperature. Live varicella-containing vaccines must be administered within 30 minutes of reconstitution.
What happens if you put varicella vaccine in the refrigerator instead of the freezer?
Vaccine will be damaged if not stored according to the manufacturer's instructions. However, it may still be possible to use vaccine that has not been properly stored. Put the affected vaccine vials into the freezer after you have marked them so they are not confused with the unaffected vials, then call the manufacturer at 1-800-9-VARIVAX (1-800-982-7482) for further guidance about whether the vaccine is still usable. Unreconstituted varicella vaccine may be stored in the refrigerator for up to 72 hours before use. If refrigerated varicella vaccine is not used within 72 hours, it should be discarded.
If you have inadvertently left your vaccine at room temperature instead of in the freezer or have experienced a power failure, label the affected vaccine to keep it separated from unaffected vaccine and return it to recommended storage conditions in a freezer promptly, then contact the manufacturer for further guidance. Do not administer the vaccine until you have consulted with Merck.
How can I transport varicella vaccine? What if I do not have access to a portable freezer?
The vaccine manufacturer does not recommend transporting varicella-containing vaccines (varicella, MMRV). If these vaccines must be transported (for example during an emergency), CDC recommends use of a portable vaccine freezer unit or qualified container and packout that maintains temperatures between -50°C and -15°C (- 8°F and +5°F). Do not use dry ice, even for temporary storage. Dry ice might expose the vaccines to temperatures colder than -50°C (-58°F).
Follow these steps for transporting frozen vaccines:
Place a temperature monitoring device (preferably with a buffered probe) in the container as close as possible to the vaccines.
  Immediately upon arrival at the destination, unpack the vaccines and place them in a freezer at a temperature range between -50°C and -15°C (-58°F and +5°F) . Any stand-alone freezer that maintains these temperatures is acceptable.
  Record the time vaccines are removed from the storage unit and placed in the transport container, the temperature during transport, and the time at the end of transport when vaccines are placed in a stable storage unit.
If necessary, varicella-containing vaccines may be transported or stored at refrigerator temperature between 2°C and 8°C (between 36°F and 46°F) for up to 72 continuous hours prior to reconstitution. To do so, follow the steps above using a portable vaccine refrigerator unit or a qualified container and packout designed to maintain vaccine storage temperatures between 2°C and 8°C (between 36°F and 46°F).
Transport of varicella-containing vaccine at temperatures other than the recommended range between -50°C and -15°C (-58°F and +5°F) is considered a temperature excursion, so contact Merck at (800) 982-7482 for further guidance. Do not discard vaccines without contacting the manufacturer and/or your immunization program for guidance.
For additional guidance, see the CDC Vaccine Storage and Handling Toolkit at www.cdc.gov/vaccines/hcp/admin/storage/toolkit/storage-handling-toolkit.pdf.
I was told by a coworker that varicella vaccine can be stored at refrigerator temperature for up to three days and still be used. Is this true?
Yes. According to the manufacturer, unreconstituted varicella vaccine may be stored at refrigerator temperature (2°C to 8°C, 36°F to 46°F) for up to 72 continuous hours prior to reconstitution. Vaccine stored at 2°C to 8°C that is not used within 72 hours of removal from -15°C (+5°F) storage should be discarded. See www.merck.com/product/usa/pi_circulars/v/varivax/varivax_pi.pdf.
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This page was updated on July 21, 2022.
This page was reviewed on September 5, 2020.
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