Drug Criteria & Outcomes-A pox on chickenpox: A guide to treating children
By Ruth Noland, PharmD
Editor, Drug Utilization Review
Varicella zoster virus (VZV) may cause varicella (chickenpox) or herpes zoster (shingles). Chickenpox manifests as an itchy vesicular skin eruption, accompanied by headache, fever, and malaise. VZV remains dormant in sensory-nerve ganglia and may be reactivated at a later time, thus presenting shingles, which manifests as a painful rash with dermatomal distribution of sensory-nerve roots.1,2
There are approximately 300,000 cases of shingles in the United States each year1 and, prior to availability of a vaccine, 4 million cases of chickenpox, 11,000 hospitalizations, and 100 deaths each year.3 Children and adolescents represent 80% of the annual varicella-related hospitalizations. Varicella complications that lead to hospitalization include bacterial skin infections, pneumonia, encephalitis, dehydration, and hepatitis.2
VZV is spread by airborne particles, usually requiring face-to-face exposure, but it also can be contracted by susceptible people through indirect air exposure. The period during which the virus is contagious is thought to be between two days before and four days after the appearance of vesicles, or until the vesicles have crusted over.1,2,4
Nearly all people who live in the United States develop varicella. Ninety percent of cases of chickenpox occur in patients under age 15; more than 90% of adults are immune to VZV.3 Illness after re-exposure is rare but may occur with immunocompromised individuals. Re-exposure to wild-type VZV in an otherwise healthy person often boosts antibodies without clinical signs of disease.2 Infection caused by VZV typically confers lifetime immunity.2
In 1995, the FDA granted approval for Varivax (varicella virus vaccine, Merck), a live attenuated vaccine, for individuals 12 months and older who have not had varicella. Among 6,889 susceptible children ages 12 months to 12 years, a single 0.5 mL dose of the vaccine given subcutaneously (SC) has resulted in seroconversion in >97% of vaccinated people. Antibodies were found in 97% of Japanese children seven to 10 years after they were given the vaccine.
Follow-up at 20 years showed antibody levels even higher than those seen 10 years earlier, presumably due to boosting of immunity from the vaccine by subsequent exposure to wild-type VZV.2
Among those vaccinated at age 13 or older, 78% of subjects seroconverted with one dose of vaccine; 99% seroconverted following a second dose four to eight weeks later.2
VZV vaccine should be given to children 12 months to 12 years old and should be routine in children 12 to 18 months old. Children with a history of chickenpox are considered immune.2,5 Adolescents and adults without a history of chickenpox also should be vaccinated, especially health care workers, day care workers, teachers, college students, military personnel, prisoners, non-pregnant women of childbearing age, international travelers, and family contacts of immunocompromised people.1-2
The varicella vaccine should not be given routinely to immunocompromised people or to pregnant women.6
Approximately 15% of people will have shingles during their lifetimes. Shingles occurs most often in the immunocompromised and the elderly.2 Octogenarians have a one in 100 chance per year of developing shingles.1 Importantly, shingles occurs less frequently in vaccinated persons than in those who experienced wild-type varicella.6
References
1. Zaia JA, Grose C. "Varicella and Herpes Zoster." In: Gorbach SL, Bartlett JG, Blacklow NR, eds. Infectious Diseases. 2nd ed. Philadelphia: W.B. Saunders Company; 1998, pp. 1311-1320.
2. Prevention of varicella: Recommendations of the advisory committee on immunization practices (ACIP). MMWR 1996; 45(RR11):1-25.
3. Prevention of varicella: Updated recommendations of the advisory committee on immunization practices (ACIP). MMWR 1999; 48(RR6):1-5.
4. Watson B, Seward J, Yang A, et al. Postexposure effectiveness of varicella vaccine. Pediatrics 2000; 105:84-88.
5. American Academy of Pediatrics, Committee on Infectious Diseases. Recommended childhood immunization
schedule-United States, January-December 2000. Pediatrics 2000; 105:148-151.
6. Klein JO. "Immunization of Children and Adults." In: Gorbach SL, Bartlett JG, Blacklow NR, eds. Infectious Diseases. 2nd ed. Philadelphia: W.B. Saunders Company; 1998, p. 448.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content