Definitions of the classes (I - III) of evidence are provided at the end of the "Major Recommendations" field.
Children 12 Months Through 12 Years of Age
Both monovalent varicella vaccine and measles-mumps-rubella-varicella (MMRV) vaccine have been licensed for use in healthy children 12 months through 12 years of age. Children in this age group should receive two 0.5-mL doses of varicella vaccine administered subcutaneously, separated by at least 3 months (evidence grade I). The recommendation for at least a 3-month interval between doses is based on the design of the studies that evaluated 2 doses in this age group (Kuter et al., 2004); if the second dose is administered inadvertently between 28 days and 3 months after the first dose, the second dose does not need to be repeated (evidence grade III). The American Academy of Pediatrics recommends the use of combination vaccines when all vaccine components are indicated to minimize the number of injections children receive. (Advisory Committee on Immunization Practices (ACIP), American Academy of Pediatrics (AAP) & American Academy of Family Physicians (AAFP), 1999)
All children routinely should receive the first dose of varicella-containing vaccine at 12 to 15 months of age (evidence grade I). The varicella vaccine should be administered to all children in this age range unless there is evidence of immunity to varicella-zoster virus (VZV) (see "Documentation of Immunity" in these recommendations) or a contraindication to administration of the vaccine (see "Contraindications" in these recommendations). The second dose of varicella-containing vaccine is recommended routinely when children are 4 to 6 years of age (i.e., before a child enters kindergarten or first grade) but can be administered at an earlier age (evidence grade III). A routine health maintenance visit at 11 to 12 years of age is recommended for all adolescents to evaluate immunization status and administer necessary vaccines, including varicella vaccine.
People > 13 Years of Age
People >13 years of age without evidence of immunity should receive two 0.5-mL doses of varicella vaccine separated by at least 28 days (evidence grade I). The recommendation for at least a 28-day interval between doses is based on the design of the studies that evaluated 2 doses in this age group. For people who previously received only 1 dose of varicella vaccine, a second dose is necessary to provide evidence of immunity. Monovalent varicella vaccine, but not MMRV vaccine, is licensed for use in this age group.
Documentation of Immunity
Only doses of vaccine for which written documentation of the date of administration is presented should be considered valid. Neither a self-reported dose nor a history of immunization of the child as provided by a parent is, by itself, considered adequate documentation of immunity. A health care professional should supply an immunization record for a patient if that health care professional has administered the vaccine or has seen a record that documents immunization. People who lack either adequate documentation of immunization or other evidence of immunity should be immunized.
Although parental self-reporting of varicella disease has historically been considered valid enough to count as evidence of immunity, recent data on self-reporting in the varicella-vaccine era have revealed it to be less reliable than in the prevaccine era, (Perella et al., 2005) probably because of the decrease in disease incidence and the proportion of mild cases among vaccine recipients, which are less readily recognized.
Serologic screening for VZV immunity generally is neither necessary nor recommended if a person has other acceptable evidence of immunity to the disease. With the exception of women who are known to be pregnant (see "Prenatal Screening and Postpartum Immunization" in these recommendations), people who lack acceptable evidence of immunity generally should be immunized without serologic testing. Postimmunization serologic testing to verify an immune response to varicella vaccine is not recommended, because available commercial assays are not sensitive enough and may give false-negative results.
Evidence of immunity to VZV in the pediatric population includes any of the following:
- Documentation of 2 appropriately timed doses of varicella vaccine (evidence grade I)
- Laboratory evidence of immunity or laboratory confirmation of disease (evidence grade I)
- Varicella diagnosed by a health care professional or verification of history of varicella disease (evidence grade III)
- For people reporting or presenting with typical disease, verification can be performed by any health care professional (e.g., school or occupational clinic nurse, nurse practitioner, physician assistant, physician).
- For people reporting or presenting with atypical and/or mild cases, assessment by a physician or physician's designee is recommended, and 1 of the following should be sought: (a) an epidemiologic link to a typical varicella case or to a laboratory-confirmed case, or (b) evidence of laboratory confirmation, if it was performed at the time of acute disease. When such documentation is lacking, people should not be considered as having a valid history of disease, because other diseases may mimic mild atypical varicella.
- History of herpes zoster diagnosed by a health care professional (evidence grade II-2)
Prenatal Screening and Postpartum Immunization
Prenatal screening of pregnant adolescent women for VZV immunity using the aforementioned criteria is recommended (evidence grade III). Varicella vaccine should not be administered to pregnant women, because the possible effects on fetal development are unknown, although no pattern of malformation has been identified after inadvertent immunization of pregnant women. After completion or termination of pregnancy, women who do not have evidence of VZV immunity should be immunized with the monovalent varicella vaccine before discharge from the hospital, birthing center, or abortion clinic; the second dose should be administered at least 28 days later (evidence grade III). Women should be counseled to avoid conception for 1 month after each dose of varicella vaccine.
A pregnant mother or other household member is not a contraindication for immunization of a child in the household (evidence grade III). Monovalent varicella vaccine should be administered to nursing mothers who lack evidence of immunity (evidence grade III).
Immunization of Immunocompromised Populations
General Recommendations
Varicella vaccine should not be administered routinely to children who have congenital or acquired T-lymphocyte immunodeficiency, including people with leukemia, lymphoma, and other malignant neoplasms affecting the bone marrow or lymphatic systems, as well as children receiving long-term immunosuppressive therapy. Certain children infected with human immunodeficiency virus (HIV) are an exception, as discussed later. Children with impaired humoral immunity may be immunized. Immunodeficiency should be excluded before immunization in children with a family history of hereditary immunodeficiency. The presence of an immunodeficient or HIV-seropositive family member does not contraindicate vaccine use in other family members.
When immunizing people with altered immunity against chickenpox (see "HIV Infection" in these recommendations), only monovalent varicella vaccine should be used. The Oka vaccine strain remains susceptible to acyclovir, and if a high-risk patient develops vaccine-related varicella, then acyclovir should be used as treatment.
Acute Lymphocytic Leukemia
Before routine immunization of healthy children against varicella was instituted in the United States in 1995, many young children with leukemia were susceptible to chickenpox. To protect them against serious and fatal varicella, a research protocol for immunization against chickenpox was put in place, but this has since been terminated. (American Academy of Pediatrics, Varicella, 2006) Considering the variability of chemotherapy regimens and the current decreasing incidence of varicella in the United States, however, these high-risk children should not be routinely immunized. Immunization of varicella-susceptible leukemic children in remission should be undertaken only with expert guidance and with the availability of antiviral therapy, should complications occur.
Live-virus vaccines usually are withheld for an interval of at least 3 months after immunosuppressive cancer chemotherapy has been discontinued. (Kroger et al., 2006; American Academy of Pediatrics, "Immunizations," 2006) The interval until immune reconstitution varies with the intensity and type of immunosuppressive therapy, radiation therapy, underlying disease, and other factors. Therefore, it often is not possible to make a definitive recommendation for an interval after cessation of immunosuppressive therapy when live-virus vaccines can be administered safely and effectively. (American Academy of Pediatrics, "Immunizations," 2006)
HIV Infection
Screening for HIV infection is not indicated before routine VZV immunization. After weighing potential risks and benefits, varicella vaccine should be considered for HIV-infected children in CDC class 1 with a CD4+ T-lymphocyte percentage of >15% (evidence grade II-1). (American Academy of Pediatrics, "Varicella-zoster," 2006) Eligible children should receive 2 doses of monovalent varicella vaccine with a 3-month interval between doses and return for evaluation if they experience a postimmunization varicella-like rash. With increased use of varicella vaccine and the resulting decrease in incidence of varicella in the community, exposure of immunocompromised hosts to VZV will decrease. As the risk of exposure decreases and more data are generated on the use of varicella vaccine in high-risk populations, the risk versus benefit of VZV immunization in HIV-infected children will need to be reassessed.
Children Who Receive Corticosteroids
Varicella vaccine should not be administered to people who are receiving high doses of systemic corticosteroids (>2 mg/kg per day of prednisone or its equivalent or 20 mg/day of prednisone or its equivalent) for >14 days (evidence grade III). The recommended interval between discontinuation of corticosteroid therapy and immunization with varicella vaccine is at least 1 month. Varicella vaccine may be administered to people on inhaled, nasal, and topical steroids.
Households With Potential Contact With Immunocompromised People
Transmission of vaccine-strain VZV from healthy people has been documented in 5 instances, resulting in 6 secondary cases. Even in families with immunocompromised people, including people with HIV infection, no precautions are needed after immunization of healthy children in whom a rash does not develop. Immunized people in whom a rash develops should avoid direct contact with immunocompromised susceptible hosts for the duration of the rash.
Contraindications
As generally with all vaccines, administration of varicella-containing vaccines is contraindicated in people with a history of severe (anaphylactic) reaction to the vaccine or its components (i.e., neomycin or gelatin). Use of varicella-containing vaccines also is contraindicated in pregnant women and in people with known altered immunity (e.g., HIV, hematologic and solid tumors, congenital immunodeficiency, and long-term immunosuppressive therapy) except as discussed previously. People with active untreated tuberculosis should not receive MMRV vaccine.
Of note, the monovalent varicella vaccine does not contain preservatives or egg protein, and although the measles and mumps vaccines included in MMRV are produced in chicken-embryo culture, the amounts of egg cross-reacting proteins are not significant. Therefore, children with egg allergy routinely may be given MMRV vaccine without previous skin testing.
Precautions
As with other vaccines, varicella-containing vaccines should not be administered to people who have moderate or severe illness, with or without fever. Recent receipt of blood products or immune globulin also is a precaution for administration of varicella-containing vaccines, as is a family history of immunodeficiency. Thrombocytopenia or a history of thrombocytopenic purpura are precautions for receipt of MMRV vaccine. For a detailed discussion of precautions, see the section on precautions and contraindications in the varicella chapter of the Red Book. (American Academy of Pediatrics, "Varicella-zoster," 2006).
Options for Postexposure Prophylaxis
Depending on a person's risk for serious varicella disease, options for postexposure prophylaxis include active immunoprophylaxis with a varicella-containing vaccine, passive immunoprophylaxis with VariZIG (the current formulation of varicella-zoster immune globulin, available under an investigational new drug application only) or immune globulin intravenous, or chemoprophylaxis with oral acyclovir. For a full consideration of these options, please refer to the Red Book. (American Academy of Pediatrics, "Varicella-zoster," 2006)
Reporting Adverse Events
Clinically significant adverse events, regardless of whether they are suspected to have been caused by varicella-containing vaccine, should be reported to the Vaccine Adverse Event Reporting System. Forms can be obtained and submitted electronically through a secure Web site (http://vaers.hhs.gov/) or obtained by telephone at 800-822-7967.
Definitions:
US Preventive Services Task Force Rating System Of Quality of Scientific Evidence*
I. Evidence obtained from at least 1 properly designed, randomized, controlled trial.
II-1. Evidence obtained from well-designed controlled trials without randomization.
II-2. Evidence obtained from well-designed cohort or case-control analytic studies, preferentially from >1 center or group.
II-3. Evidence obtained from multiple time series with or without the intervention or dramatic results in uncontrolled experiments (such as the results of the introduction of penicillin treatment in the 1940s).
III. Opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees.
*Source: US Preventive Services Task Force. Guide to Clinical Preventive Services. 2nd ed. Alexandria, VA: International Medical Publishing; 1996;861– 865.
