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Hepatitis A: A Preventable Threat

Rosenthal, Philip

Section Editor(s): Baker, Robert D. Jr. M.D., Ph.D.; Rosenthal, Philip M.D.; Sherman, Philip M. M.D., F.R.C.P.C.; Finkel, Yigael M.D., Ph.D.

Journal of Pediatric Gastroenterology and Nutrition: November 2002 - Volume 35 - Issue 5 - p 595-596
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Professor of Pediatrics & Surgery

Medical Director, Pediatric Liver Transplant Program

Director, Pediatric Hepatology

University of California, San Francisco, U.S.A.

Disclosure: Dr. Rosenthal chairs the American Liver Foundation's Hepatitis A Vaccine Initiative. He has testified on behalf of Hepatitis A Vaccine legislation before the California, Nevada and New Mexico State Assembly and Senate Health Committees. He is a Consultant to GlaxoSmithKline, one of the hepatitis A vaccine manufacturers.

Despite the licensure of a safe and effective vaccine in 1995, hepatitis A continues to be one of the most frequently reported vaccine-preventable diseases in the United States (1). It is true that the overall incidence of hepatitis A has declined in the United States over the past few decades as a result of improved hygiene and sanitation. However, one must be careful not to be lulled into complacency regarding this apparent decline, since it is well established that the rates of hepatitis A infection have been cyclical with peaks occurring on average every 7 to 10 years. Furthermore, since many children are asymptomatic, hepatitis A is significantly underreported. The continued occurrence of community-wide outbreaks throughout the United States indicates that hepatitis A remains a public health threat. A growing number of states are currently addressing the issue of routine immunization among children, as recommended by the Centers for Disease Control and Prevention and the Advisory Committee on Immunization Practices (ACIP) (2). Currently, only the states of Oklahoma, Nevada, Alaska, and Texas have hepatitis A immunization requirements.

The United States Center for Disease Control and Prevention (CDC) recommends routine childhood immunization for those states in the U.S. with an incidence of hepatitis A that is approximately twice the 1987–97 national average, or >20 cases per 100,000 people per year. These states include Alaska, Arizona, California, Idaho, Nevada, New Mexico, Oklahoma, Oregon, South Dakota, Utah, and Washington. While these states represent only 22 percent of the United States population, they account for 50 percent of reported hepatitis A cases each year. The CDC also recommends that childhood immunization be considered in states with an annual rate of hepatitis A between 10 and 20 cases per 100,000 people. These states include Arkansas, Colorado, Missouri, Montana, Texas, and Wyoming.

Why implement a routine childhood hepatitis A immunization policy? One case of hepatitis A can result in a community-wide outbreak. Hepatitis A outbreaks occur sporadically and cannot be predicted (3). All too often, vaccine programs are not implemented until after serious outbreaks occur and needlessly affect hundreds of individuals. Hepatitis A causes a vaccine-preventable illness that is not treatable and can cause death. Up to 22 percent of U.S. adults infected with hepatitis A require hospitalization (4). Each year in the U.S., 100 individuals die due to hepatitis A, according to CDC statistics (2). In the United States, hepatitis A infection in adolescents and adults costs an estimated $488 million per year (5).

The highest rates of hepatitis A infection occur among children aged 5 and 14 years. As we know, the younger the child, the more likely that he or she will have an unrecognized, asymptomatic infection, thereby serving as a source of infection for others, particularly those not protected by vaccination. Adults usually experience more severe illness than children when they are infected and, on average, miss about one month of work with hepatitis A infections (2).

The benefits of routine childhood immunization, particularly in high endemic areas, include vaccination before an established risk period and the potential to interrupt transmission by the creation of herd immunity among school-aged children. Thus, an immunized child not only protects himself or herself from the disease, but also protects others indirectly by eliminating himself or herself as a source of transmission.

What about the recommendation for the use of hepatitis A vaccination in other countries besides the United States? Certainly, this needs to be determined based upon each country's priorities for health care spending. In developing nations, hepatitis A is predominantly a childhood disease and most individuals acquire antibody by 5 years of age. It may not be cost effective to initiate a universal immunization program in childhood in many of these areas. However, individuals traveling to these areas should be aware that they may be at significant risk for contracting hepatitis A, and hence the recommendation for hepatitis A immunization for travelers to areas of high endemicity.

Individuals with chronic liver disease are prime candidates for hepatitis A vaccination as well as hepatitis B immunization. Acute hepatitis A infection in a patient with chronic liver disease could result in significant decompensation. The large number of adult patients with chronic hepatitis C awaiting liver transplantation in the United States is in this at-risk category. The approval of a combination hepatitis A and B vaccine for adult use makes immunization of these individuals much easier. Currently, there is no approved combination hepatitis A and B vaccine for use in infants and children, though the hepatitis A vaccine manufacturers are considering seeking approval of such a combination for pediatric use.

What about the use of a targeted immunization approach to reduce the incidence of hepatitis A? Previous experience with hepatitis B immunization has shown that targeting immunization to high-risk individuals alone was unsuccessful. Furthermore, the hepatitis A virus does not recognize county, state, and international borders. The ability for easy travel between areas of high and low endemicity allows for ready hepatitis A transmission.

The availability of a safe and effective hepatitis A vaccine provides the opportunity to substantially lower the incidence of this disease, potentially eradicate infection, and offset the morbidity, mortality, and healthcare costs associated with this vaccine-preventable disease. We have proven with the administration of thousands of doses of the hepatitis A vaccines that it is safe and efficacious. We have the means to eradicate this disease if we are willing to spend the resources necessary for mass immunization. We know all too well the serious medical, emotional, and financial consequences that can be exacted by hepatitis A. In my opinion, we should all be encouraging our patients and legislatures to implement measures to establish routine immunization of children against hepatitis A.

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REFERENCES

1. CDC. Summary of notifiable diseases, United States, 1997. MMWR 1998; 46:1–87.
2. CDC. Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1999; 48:1–42.
3. Bell BP, Shapiro CN, Alter MJ, et al. The diverse patterns of hepatitis A epidemiology in the United States-implications for vaccination strategies. J Infect Dis 1998; 178:1579–84.
4. CDC. Hepatitis surveillance report no. 56. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, CDC, 1996.
5. Hadler SC. Global impact of hepatitis A virus infection: changing patterns. In: Hollinger FB, Lemon SM, Margolis HS, eds. Viral hepatitis and liver disease. Baltimore, MD: Williams & Wilkins, 1991:14–20.
© 2002 Lippincott Williams & Wilkins, Inc.