Skip directly to searchSkip directly to A to Z list Skip directly to navigationSkip directly to site contentSkip directly to page options
CDC Home
Yellow Book Cover

Yellow Book

CDC Health Information for International Travel 2008

Chapter 4
Prevention of Specific Infectious Diseases

Varicella (Chickenpox)

Description

Varicella (chickenpox) is the primary infection with the varicella zoster virus (VZV). It is a highly contagious rash illness transmitted by airborne or droplet pathways. The usual incubation period is 14-16 days (range 10-21 days). Second cases of varicella have been reported in immunocompetent persons but are rare. Following varicella, VZV establishes latency in sensory nerve ganglia. The virus can reactivate later in life, causing herpes zoster (shingles), usually localized to one to three dermatomes. Transmission of VZV to a susceptible person occurs through contact with either a person with varicella or, less commonly, a person with herpes zoster.

Occurrence

Before introduction of varicella vaccine in the United States in 1995, varicella was endemic, with virtually all persons being infected by adulthood. Since implementation of the varicella vaccination program, incidence has declined in all age groups, with the greatest decline among children aged 1-4 years. Data from passive and active surveillance have indicated a decline in varicella cases of 70%-84% from 1995 through 2001 (1-3). The downward trend in varicella has continued in the United States through 2005 with an approximately 90% decline in incidence from 1995 in active surveillance sites with high vaccine coverage (CDC, unpublished data).

Risk for Travelers

Varicella and herpes zoster occur worldwide, but varicella vaccine is routinely used for vaccination of children in only some countries, including the United States, Uruguay, Qatar, Australia, Canada, Germany and South Korea. The risk of varicella infection for travelers coming to the United States is lower than for travel anywhere else in the world. However, VZV is still widely circulating in the United States. Additionally, exposure to herpes zoster, while less common than varicella, poses a risk for varicella infection. In temperate climates, in the absence of vaccination, most varicella cases are reported among preschool- and school-aged children during winter and spring. Studies suggest that in tropical areas VZV infection occurs later during childhood and adolescence resulting in higher susceptibility among adults compared with temperate climates (2). Reasons for this difference in disease epidemiology are unclear. They may relate to the agent’s heat lability and/or to factors such as the tendency for less indoor crowding in tropical regions.

Clinical Presentation

Varicella is generally a mild disease in children. It usually lasts 4-7 days and is characterized by a short (1- to 2-day) or absent prodromal period (low-grade fever, malaise) and by a pruritic rash consisting of crops of macules, papules, vesicles, and eventual crusting, which appear in three or more successive waves. Serious complications are the exception but can occur, mainly in infants, adolescents, adults, and immunocompromised persons. They include secondary bacterial infections of skin lesions, pneumonia, cerebellar ataxia, and encephalitis. Because the vaccine is 70%-90% effective, a modified varicella, known as breakthrough disease, can occur in some vaccinated persons. Breakthrough disease is most commonly (~ 70% - 80% of cases) mild, with fewer than 50 skin lesions, no fever and shorter duration of rash. The rash may be atypical in appearance with fewer vesicles and predominance of macular popular lesions. Nevertheless, breakthrough varicella is contagious and cases should be isolated for as long as lesions persist.

Prevention

Although vaccination against varicella is not a requirement for entry into any country (including the United States), persons traveling or living abroad should ensure that they are immune.

VACCINE

Varicella vaccine contains live, attenuated VZV. It is available as a monovalent formulation and in combination formulation, as measles-mumps-rubella-varicella (MMRV) vaccine, which is licensed in the U.S for children 1–12 years only. In June 2005 and June 2006, the Advisory Committee on Immunization Practices (ACIP) approved changes to the 1996 and 1999 recommendations for use of varicella-containing vaccines and approved new criteria for evidence of immunity to varicella (4-6). Two doses of varicella-containing vaccine are now recommended for routine immunization of all children younger than 13 years of age who are without contraindications. The first dose should be administered at 12 – 15 months of age and the second dose at 4 – 6 years of age. A second dose of catch-up varicella vaccination is recommended for children, adolescents, and adults who previously had received one dose. The ACIP now recommends that all others at least 13 years of age without evidence of immunity be vaccinated with two doses of varicella vaccine at an interval of 4-8 weeks. In case of uncertainty, prior varicella disease is not a contraindication to varicella vaccination.

After one dose of varicella vaccine, 85% to 90% of children achieve antibody levels that are an approximate correlate of immunity and after two doses, >99% of children achieve this antibody level. (7,8). Vaccine-induced immunity is believed to be long lasting but has not been assessed in the absence of external boosting to varicella zoster virus through exposures. Vaccine efficacy is estimated to be most commonly 80% to 85% (range 44% to 100%) against disease of any severity and 95% against severe disease (9).

Revised criteria for evidence of immunity to varicella include any of the following:

  1. Documentation of age-appropriate vaccination:
    • a. Preschool-aged children at least 12 months of age: one dose
    • b. School-aged children, adolescents, and adults: two doses
  2. Laboratory evidence of immunity or laboratory confirmation of disease
  3. Born in the United States before 1980
  4. A health-care provider’s diagnosis of varicella or a health-care provider’s verification of history of varicella disease
  5. History of herpes zoster based on health-care provider’s diagnosis

Another vaccine that contains live VZV has been recently licensed and recommended for use in the US. On October 2006, the ACIP recommended the use of a single dose of zoster vaccine for adults 60 years of age and older, whether or not they reported a prior episode of herpes zoster (10).

Adverse Reactions

The most common adverse reactions following varicella vaccine are injection site complaints (pain, soreness, redness, and swelling) that are self-limited. In uncontrolled trials, fever was reported in 15% of children and 10% of adolescents and adults. A macular or vaccine rash usually consisting of a few lesions at the injection site is reported in 3% of children and 1% of adolescents and adults after the second dose. A generalized rash with a small number of lesions may rarely occur, within 3 weeks of vaccination.

Varicella vaccine is a live-virus vaccine and results in a latent infection similar to that caused by wild VZV. Consequently, zoster caused by the vaccine virus has been reported. This appears to occur at a lower rate than following natural infection but longer term follow up is needed. Not all reported cases have been confirmed as having been caused by vaccine virus; some were caused by the wild virus.

Precautions and Contraindications
Allergy

Persons with severe allergy (hives, swelling of the mouth or throat, difficulty breathing, hypotension, and shock) to gelatin or neomycin or who have had a severe allergic reaction to a prior dose should not be vaccinated with varicella vaccine. Varicella vaccine does not contain egg protein or preservative.

Immunosuppression

Persons with immunosuppression of cellular immune function resulting from leukemia, lymphomas of any type, generalized malignancy, immunodeficiency disease, or immunosuppressive therapy should not be vaccinated. Treatment with low-dose prednisone (e.g., <2 mg/kg of body weight/day or <20 mg/day) or aerosolized steroid preparations is not a contraindication to varicella vaccination. Persons whose immunosuppressive therapy with steroids has been stopped for 1 month (3 months for chemotherapy) may be vaccinated. In addition, persons with impaired humoral immunity may now be vaccinated. Because children infected with HIV are at greater risk for morbidity from varicella and herpes zoster than are healthy children, the ACIP recommends that varicella vaccine should be considered for HIV-infected children at least 12 months of age in CDC clinical class N, A, or B with CD4 T-lymphocyte counts of at least 15% and without evidence of varicella immunity (4). Eligible children should receive two doses of single-antigen varicella vaccine, with a minimum 3-month interval between doses. The use of varicella vaccine in other HIV-infected children is being investigated.

No adverse events following varicella vaccination related to the use of salicylates (e.g., aspirin) have been reported to date. However, the manufacturer recommends that vaccine recipients avoid the use of salicylates for 6 weeks after receiving varicella vaccine because of the association between aspirin use and Reye syndrome following varicella.

Pregnancy

Women known to be pregnant or attempting to become pregnant should not receive varicella vaccine. Pregnancy should be avoided for 1 month following varicella vaccination. Breastfeeding is not a contraindication to the varicella vaccination.

POSTEXPOSURE PROPHYLAXIS

Use of Vaccine

Administration of varicella vaccine to susceptible healthy persons within 72 hours and possibly up to 120 hours after varicella exposure may prevent or significantly modify disease and should be considered in these circumstances. Physicians should advise parents and their children that the vaccine may not protect against disease in all cases. In several studies protective efficacy was 90% when children were vaccinated within 3 days of exposure (5).

Use of Varicella Zoster Immune Globulin (VZIG)

In certain circumstances, postexposure prophylaxis with VZIG is recommended. The decision to administer VZIG to a person exposed to varicella should be based on 1) whether the patient is susceptible, 2) whether the exposure is likely to result in infection, and 3) whether the patient is at greater risk for complications than the general population (immunocompromised persons, pregnant women, neonates whose mothers had signs and symptoms of varicella within 5 days before and 2 days after delivery, and premature neonates exposed postnatally). VZIG provides maximum benefit when it is administered as soon as possible after the presumed exposure, but it may be effective if administered as late as 96 hours after exposure. The product currently in use in the United States, VariZIGTM (Cangene Corporation, Winnipeg, Canada), is available under an Investigational New Drug protocol. VariZIG can be obtained from the US sole authorized distributor, FFF enterprises (Temecula, California) (24-hour telephone, 800-843-7477, http://www.fffenterprises.com) (11).

GENERAL VACCINE RECOMMENDATIONS, PEDIATRIC AND CATCH-UP SCHEDULES, AND RECOMMENDATIONS FOR SPECIAL POPULATIONS

Refer to Chapters 1, 8 and 9.

Treatment

Acyclovir, as well as other antiviral medications have been used in various circumstances for treatment of some individuals with varicella. Oral Acyclovir is not indicated for treatment of otherwise healthy children but is recommended for treatment of adolescents and adults. Oral Acyclovir is not recommended for postexposure prophylaxis.

 

  1. Seward JF, Watson BM, Peterson CL, Mascola L, Pelosi JW, Zhang JX, et al. Varicella disease after introduction of varicella vaccine in the United States, 1995-2000. JAMA. 2002;287:606-11.
  2. Gershon AA, Takahasi M, Seward J. Varicella vaccine. In: Plotkin SA, Orenstein WA, eds. Vaccines. 4th ed. Philadelphia: Saunders; 2004:783-823. CDC_ch04_113-380.indd 354 4/9/07 10:06:52 AM Viral Hemorrhagic Fevers 355
  3. CDC. Decline in annual incidence of varicella – Selected States, 1990-2001. MMWR Morbid Mortal Wkly Rep. 2003;52:884-5.
  4. Centers for Disease Control. Prevention of varicella: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Morb Mort Wkly Rep. 1996;45:1-36.
  5. Centers for Disease-Control. Prevention of varicella. Update. MMWR Morbid Mortal Wkly Rep. 1999;48:1-6.
  6. ACIP Provisional Recommendations for Prevention of Varicella (http://www.cdc.gov/nip/vaccine/varicella/varicella_acip_recs_ prov_june_2006.pdf). Accessed November 21, 2006.
  7. Kuter B, Matthews H, Shinefi eld H, Black S, Dennehy P, Watson B, et al. Ten year follow-up of healthy children who received one or two injections of varicella vaccine. Pediatr Infect Dis J. 2004;23:132-7.
  8. Shinefield H, Black S, Digilio L, Reisinger K, Blatter M, Gress JO, et al. Evaluation of a quadrivalent measles, mumps, rubella and varicella vaccine in healthy children. Pediatr Infect Dis J. 2005;24:665-9.
  9. Seward JF. Update on varicella. Pediatr Infect Dis J. 2001;20:619-21.
  10. ACIP Provisional recommendations for the use of zoster vaccine (http://www.cdc.gov/nip/recs/provisional_recs/zoster-11-20-06. pdf). Accessed 21 November 2006.
  11. CDC. A new product (VariZIG) for postexposure prophylaxis of varicella available under an Investigational New Drug application expanded access protocol. MMWR Morbid Mortal Wkly Rep. 2006; 55(MM8):209-210
MONA MARIN, AISHA JUMAAN, GARY BRUNETTE

 

  • Page last updated: January 07, 2009
  • Content source:
    Division of Global Migration and Quarantine
    National Center for Preparedness, Detection, and Control of Infectious Diseases
Contact Us:
  • Centers for Disease Control and Prevention
    1600 Clifton Rd
    Atlanta, GA 30333
  • 800-CDC-INFO
    (800-232-4636)
    TTY: (888) 232-6348
    24 Hours/Every Day
  • cdcinfo@cdc.gov
USA.gov: The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30333, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348, 24 Hours/Every Day - cdcinfo@cdc.gov