September 1996
SEATTLE — Child care workers usually are at low risk for occupational exposure to hepatitis A virus (HAV), so routinely immunizing them against the virus may not be indicated, according to a recent study. However, immunizing child care workers against HAV may prevent disease during outbreaks, the researchers said.
"If outbreaks are recognized early enough, vaccination of child care providers against hepatitis A might prevent transmission to providers in outbreak settings," the investigators, led by Lisa A. Jackson, MD, MPH, stated in The Pediatric Infectious Disease Journal.
"The decision of whether routine vaccination of child care workers is indicated for prevention of outbreak-associated cases should incorporate consideration of the estimated frequency of HAV outbreaks in child care facilities, as well as the estimated cost effectiveness of a routine vaccination program," they said.
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During HAV outbreaks at child care facilities, attack rates of up to 15% have been reported among the staff, Jackson and colleagues pointed out. Contact with soiled diapers is the most significant risk factor for HAV infection among child care center staff during an outbreak.
The virus is spread by the fecal-oral route. HAV usually does not cause symptoms in children, but it can cause prolonged illness in adults. Clinical features include malaise and jaundice.
The hepatitis A vaccine is indicated for people at high risk for contracting HAV infection, such as people traveling to places where hepatitis A is endemic. Some researchers have suggested that child care workers in developed nations have an increased risk for hepatitis A and should be immunized against the virus.
Jackson and colleagues based their conclusions on a study of 360 child care workers in King County, Wash. They obtained blood samples from child care workers and tested those samples for antibodies to HAV, as well as hepatitis B and C, cytomegalovirus (CMV), varicella and measles. Investigators also gave subjects a questionnaire to assess employment characteristics and other potential risks for infection. Jackson and colleagues also compared the seropositivity rate among providers with that of subjects who participated in the Third National Health and Nutrition Survey (NHANES), which included a representative sample of the U.S. population.
Of 313 American-born child care providers, 26 (8%) were seropositive, a rate lower than that of NHANES subjects. "This evidence does not appear to support routine vaccination of child care workers," said Jackson, who is with the University of Washington School of Public Health here, where she is a senior fellow in the department of epidemiology.
The low prevalence of past HAV infection among the subjects is consistent with the low prevalence of HAV infection among young American children, according to the investigators.
The study also found a higher rate of HAV seroprevalence among foreign-born subjects. Twenty-two of the 47 people born outside the United States were seropositive, for a 46% seroprevalence rate among foreign-born subjects.
Anti-HAV seropositivity also was associated with age, income and Hispanic ethnicity, but not with employment characteristics.
In addition, 221 providers (62%) had antibodies to CMV. After controlling for age in multivariate analysis, the presence of these antibodies was associated with non-white race, changing diapers three days or more per week while at work and having a child in the household. Furthermore, seropositivity increased with age. The mean age of people seropositive for CMV was 34.9 years, compared with 31.6 years for people who were seronegative.
Child care workers are known to have a higher rate of cytomegalovirus (CMV) infection than people who do not work in a child care setting. Consequently, the relatively high rate of CMV seropositivity and the risk factors for infection suggest that the study population may be representative of child care workers in general in the United States, thus validating the HAV findings, Jackson said.
The prevalence of antibodies to HBV, HCV, measles and varicella was 1.4%, 0.6%, 94% and 98%, respectively.
For more information:
- Jackson LA, Stewart LK, Solomon SL, et al. Risk of infection with hepatitis A, B or C, cytomegalovirus, varicella or measles among child care providers. Pediatr Infect Dis J. 1996;15:584-9.
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