Varicella poses serious risk for unvaccinated adults
Each varicella case could cost hospital $2,000
Varicella poses a serious health threat to some adults who have not had the disease and have not been vaccinated. The Centers for Dis ease Control and Prevention urges health care facilities to vaccinate as many employees as possible against the disease, says Jane Seward, MD, chief of varicella activity for the National Immu nization Program at the Centers for Disease Con trol and Prevention in Atlanta.
A recent CDC report described five fatal cases of adult varicella in Florida. Complications of varicella (which occur primarily among adults) include soft-tissue infections, necrotizing fasciitis, pneumonia, cerebellar ataxia, and encephalitis, according to the Immunization Action Coalition. Mortality rates in adults are estimated to be 30.9 per 100,000 infected adults, almost 30 times the rate for healthy children. Approximately 1.6% of infected adults require hospitalization.1 The disease can be particularly dangerous for immunocompromised adults and women in their third trimester of pregnancy.
The financial burden of varicella outbreaks in health care facilities can be daunting. One case can cost a hospital more than $2,000 when factors such as outpatient care, time lost from work, and hospitalization are considered. The investigation and containment of one 1984 hospital outbreak of varicella cost $19,000.2 The cost of one year of varicella control, including work furloughs, serology, patient isolation, epidemiological investigation, and varicella zoster immune globulin can easily reach $41,500, according to another report, and $56,000 according to a third.3
The vaccine, however, does not guarantee immunity, providing protection to 70% to 90% of recipients against a typical case of varicella. It is 95% effective against severe illness. Research ers have determined that use of the varicella vaccine (Varivax, Merck & Co., West Point, PA) "substantially" cuts the cost of varicella control in hospitals.4 A second study found that varicella vaccination of susceptible health care workers can reduce costs and decrease morbidity.5 More recent anecdotal evidence supports such claims. (See cover story on varicella, p. 109.)
Walter A. Orenstein, MD, assistant surgeon general and director of the National Immuniza tion Program at the CDC, states that "most persons who develop varicella who have previously been vaccinated tend to have very mild illness, with fewer than 50 skin lesions, compared to 200 to 500 skin lesions in a typical unvaccinated case. Despite the proven efficacy of varicella vaccine, vaccination rates have been low."
He adds that the rate of herpes zoster (shingles) cases secondary to varicella vaccination is lower than expected, and that the vaccine will "probably reduce the incidence of shingles." Also, transmission of the virus from vaccinated adults to people who have not been vaccinated occurs very rarely, and only when a rash occurs after the injection. Of an estimated 11 million doses of vaccine distributed, only one case of post-vaccination transmission of full-blown vari cella has been published, according to Orenstein. "The risk of transmission is more than outweighed by the great benefits provided by vaccine," he says.
90% of pre-vaccine cases occurred in children
Varicella is most serious when it strikes adults, though children serve as the primary source of transmission to groups at higher risk for severe disease. CDC data show that that only 34% of three-year-old children received varicella vaccinations last year. According to Seward, that proportion is certainly higher now, yet the CDC’s goal is to vaccinate 90% to 95% of children by the time they enter the school system.
Before the availability of varicella vaccine, four million varicella cases were reported each year in the United States, 90% of which occurred in children, according to the CDC. The disease has been responsible for 11,000 hospitalizations and 100 deaths annually in this country. The CDC soon will publish amended data gathered after the varicella vaccine became available in 1995.
References
1. Preblud SR. Varicella: Complications and costs. Pediatrics 1986; 78(Suppl):728-735.
2. Hyams PJ, Stuewe MCS, Heitzer V. Herpes zoster causing varicella in hospital employees: Cost of a casual attitude. Am J Infect Control 1984; 12-25.
3. Krasinski K, Holzman RS, LaCouture R, et al. Hospital experience with varicella-zoster virus. Infect Control 1986; 7:312-316.
4. Tennenberg AM, Brassard JE, Van Lieu J, et al. Varicella vaccination for healthcare workers at a university hospital: An analysis of costs and benefits. Infect Control Hosp Epidemiol 1997; 18:405-411.
5. Nettleman MD, Schmid M. Controlling varicella in the healthcare setting: The cost effectiveness of using varicella vaccine in healthcare workers. Infect Control Hosp Epidemiol 1997; 18:504-508.
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