Hepatitis A is a ‘community disease’

October 2002

---Philip A. Brunell, MD

Infectious hepatitis or hepatitis A does not produce a carrier state or chronic liver disease but it is responsible for significant morbidity. In young children it is often asymptomatic but it can cause illness-requiring absence from school and sometimes hospitalization in older children. Because it usually occurs in the absence of jaundice in infants, they frequently spread the infection to contacts. Outbreaks in day care centers often defined by cases occurring in three families of attendees of a single center. The day care attendees usually will be asymptomatic and only by detecting cases in their contacts can an epidemic be recognized. The illness is much more severe in adults and may lead to hospitalization and long periods of convalescence.

Hepatitis A may be thought of as a “community disease.” There are certain communities where the disease is much more prevalent than others. Vaccine programs have focused on these communities. The decision to recommend routine immunization is based on the rate of hepatitis A in a given state or community. The national average is 1/10,000 reported cases. However, serologic surveys have indicated that this badly underestimates the actual frequency of disease (Pediatrics. 2002;109:839) probably because of the high rate of subclinical infection in young children. In communities with rates of 2/10,000 or more, routine childhood immunization is recommended. Of the eleven states in this category (Alaska, Arizona, California, Idaho, Nevada, New Mexico, Oklahoma, Oregon, South Dakota, Utah and Washington), only four have mandated routine immunization of children. The reticence is budgetary, as the vaccine is expensive, and states that do recommend routine immunization have to provide some of the funding. Most states are not awash with money these days. Children in these states who are Vaccines for Children-eligible can be immunized under this program. Routine immunization of children in areas where the rates are high has produced a dramatic decrease of hepatitis A in all age groups (JAMA. 2001;286:2968).

In states with intermediate rates (>1:10,000 and <1:20,000) some communities with particularly high rates have recommended routine immunization of children and recommendations for the entire state “should be considered.” At the present time, hepatitis A vaccine is not recommended for children younger than 2 years. Maternal antibody has been shown to interfere with the antibody response although it is unlikely to be a problem in the older children in the younger than 2 groups. In some countries, it has been used in children younger than 2. Although it has been shown to terminate outbreaks, it is not recommended for postexposure use. Immune globulin intramuscular (IGIM) is recommended. Some have used both and, although this blunts the antibody response, the second dose produces a protective titer.

Unless there is epidemiologic linkage it often is difficult to separate the various types of hepatitis clinically. I have even seen autoimmune hepatitis present as acute hepatitis which resembled infectious hepatitis. Laboratory confirmation usually is needed for diagnosis. Although IGIM should be given as soon as possible following exposure, it can be delayed as long as two weeks if it is necessary to obtain laboratory confirmation of the diagnosis. Exposure to day care attendees usually is a good epidemiologic marker for a diagnosis of hepatitis A. Day care outbreaks usually occur in communities with high rates of hepatitis. Immunization of day care workers is not routinely recommended in areas of low prevalence; nor is immunization of health care workers. Immunization of those at high risk, e.g., travellers to endemic areas, individuals with chronic liver disease and men having sex with men, et al, is recommended for individuals in low and high prevalence areas. It is important to remember that about one-third of the cases of hepatitis A in travelers occur in children. Although most vaccinees will have antibody two weeks postimmunization, it is recommended that vaccination be given a month prior to the start of travel. For those who cannot be immunized on time IGIM is recommended. Although the second dose is recommended 6 to 12 (for Havrix [GlaxoSmithKline]) or 6-18 months (for Vaqta [Merck]) the series should not be restarted if this interval is exceeded. The vaccines should be considered interchangeable.

It is likely that universal immunization against hepatitis A will be recommended in the future; at the present the indications are somewhat restricted. But it is important to be cognizant of the need to immunize those for whom the vaccine is indicated.

For more information:

• CDC. Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices. MMWR. 1999;48:RR-12.
• See also http://www.immunize.org/catg.d/p2021a.htm.