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Hepatitis B Virus Infection

Most hepatitis B virus (HBV) infections occur in adolescents and adults but the consequences of infection in early childhood have long lasting and serious consequences, including liver cancer, chronic liver disease and death. Although hepatitis B is often thought of as a disease that affects people who are sexually active or who use intravenous drugs, in fact nearly one out of three patients who contract this disease have no known source of infection.

HBV causes an acute (short duration) infection in some and a long-lasting (or, chronic) infection in others.

•  Symptoms of HBV infection vary:
  • More than half of the people infected with HBV show no signs or symptoms at the time of infection.
  • Some develop symptoms of hepatitis (loss of appetite, fatigue, nausea, jaundice (yellow eyes and skin), joint pain, and skin rashes).
• Some become chronically infected, presenting a risk to others. Those with chronic infection also are at risk for developing liver disease, including liver cancer, later in life. The risk for acquiring chronic infection varies by age at initial infection. For example, the risk of becoming chronically infected is
  • Approximately 90% for infants who are infected from their mothers at birth. 
  • Between 30 and 50% for children infected before five years of age. 
  • Between 6 and 10% for adults.

The Consequences of HBV Infection

The consequences of acute HBV infection can be serious. However some of the most serious outcomes from HBV infection occur many years or decades later in those who are chronically infected. For example, about 25% of infants and young children with chronic infection will die prematurely as adolescents or, more typically, as adults from liver disease or liver cancer.1

For these reasons, prevention of HBV transmission from person to person early in life is important.

HBV causes 5,000 deaths each year in the United States, including 3,000–4,000 from cirrhosis and approximately 1,000–1,500 from primary liver cancer.

The estimated medical and work loss cost per year of HBV is $700 million in the U.S.2 About 1.25 million people in the US have chronic HBV infection; worldwide, more than 350 million people have chronic HBV infection.

Hepatitis B Vaccine

The current hepatitis B vaccine has been used in the United States since 1986. Initially the vaccine was recommended only for people who were identified to be at a high risk for acquiring the infection. In 1991, the recommendation was extended to include all infants as well. In 1995 and 1999, the universal hepatitis B vaccine recommendations were extended to all children less than 18 years of age. In 2005, a comprehensive strategy to eliminate HBV transmission in the US was published1 that includes newborn immunization beginning at birth and aggressively identifying infected mothers and treating their newborns.

Hepatitis B vaccine is protective against both acute and chronic HBV infections, reducing the risks of all HBV complications, including liver cancer.1 Even if antibody wanes over time the vaccinated person appears to continue to be protected. Usually 3 doses of vaccine are required to provide protection.

Between 1990 and 2002, acute hepatitis B declined from 21,102 cases reported to 8,064.3 The incidence of acute hepatitis B among children and adolescents declined 89%4 and the prevalence of chronic HBV infection was also reduced.5

After a decade, a program?that was begun in 1992 in British Columbia targeting hepatitis b immunization of 11 year old children?reduced HBV transmission, eliminating HBV infection in adolescents.6.

Hepatitis B vaccine has proven to be extremely safe, including when given to newborns, children, and adolescents.4 5 7 Local temporary pain at the injection site occurs in about ofne third of vaccines and low grade fever can occur as well. A very small number of people should not receive the hepatitis B vaccine, such as those who have had a life-threatening allergy to baker’s yeast or a previous dose of the vaccine.

Concerns About Hepatitis B Vaccine

Some parents resist hepatitis B immunization for their children because of vaccine safety concerns or uncertaintly about their child’s risk of exposure to the HBV.8

Hypotheses that a number of chronic illnesses might be caused by Hepatitis B vaccine have not been able to be substantiated. For example, the Institute of Medicine Vaccine Safety Review Committee concluded that the data favored rejection of an association between multiple sclerosis and hepatitis B vaccine administration; there was insufficient data, however, to exclude an association with other demyelinating diseases.9

Some parents regard hepatitis B immunization as unnecessary, based on the misconception that this is a disease for which their children are not at risk. These parents think that hepatitis B is a disease mainly of intravenous drug users, sex workers, men who have sex with men, healthcare workers (largely because of accidental needle stick exposure) and prison inmates.

Why Parents Should Vaccinate Their Children against HBV

While HBV is most effectively transmitted from one person to another through blood and body fluids by sexual contact, injection drug use, or occupational exposure,

•  As many as 16%-30% of hepatitis B cases have no known source of infection.10 11
• Mothers who have chronic HBV infection can transmit the virus to their newborns. They are often unaware that they are HBV infected. There are specific recommendations for the management of infants born to either HBV infected mothers or to mothers with unknown HBV infection status.1
• For children, the most common sources of HBV infection is from their mother at birth or subsequently, or by transmission from an infected household contact.2 
• Unvaccinated children in families with no known risk factors are still at risk of infection through normal play activities. The sources of their infection are unknown but HBV could be transmitted through contact of non-intact skin (as occurs in school yard abrasions), by sharing contaminated inanimate objects (such as toothbrushes, towels, or bed sheets), and by being bitten.12 13 14 Thus, children whose families seemingly are not at risk of HBV infection may also be at risk of becoming HBV-infected, as there is no way to know which child will eventually be exposed. 
• Teenagers have increased risk of HBV exposure when they become sexually active.

For these reasons, HBV vaccine is recommended for everyone 18 years and younger, starting with the first dose shortly after birth (prior to discharge from the newborn nursery).1 Of course, anyone with risk factors should also be immunized no matter what their age.1

References

• 1. a. b. c. d. e. f. Centers for Disease Control and Prevention (CDC). (2005). A comprehensive immunization strategy to eliminate transmission of hepatitis B virus infection in the United States. Recommendations of the Advisory Committee on Immunization Practices (ACIP). Part 1: Immunization of infants, children, and adolescents. MMWR 54 (RR-16); 1-32.
• 2. a. b. The American Liver Foundation. Hepatitis and Liver Disease in the United States.
• 3. CDC (2004) Incidence of acute hepatitis B?United States, 1990-2002. MMWR 52; 1252-5.
• 4. a. b. Shepard CW, Finelli L, Fiore AE, et al. (2005) Epidemiology of hepatitis B virus infection in United States children. Pediatr Infec Dis J 24; 755-60.
• 5. a. b. CDC. Achievements in Public Health: Hepatitis B vaccination-United States, 1982-2002. MMWR June 28, 2002; 51: 549-563.
• 6. Patrick DM, Bigham M, Ng H, et al. (2003). Elimination of acute hepatitis B among adolescents after one decade of an immunization program targeting Grade 6 students. The Pediatric Infectious Diseases Journal 22; 874-878.
• 7. Lewis E, Shinefield HR, Woodruff BA, et al (2001). Safety of neonatal hepatitis B vaccine administration. Pediatric Infectious Disease Journal 20:1049-54.
• 8. Bardenheier B, Yusuf H, Schwartz B, et al (2004). Are Parental Vaccine Safety Concerns Associated With Receipt of Measles-Mumps-Rubella, Diphtheria and Tetanus Toxoids With Acellular Pertussis, or Hepatitis B Vaccines by Children? Archives of Pediatric and Adolescent Medicine 158:569-575.
• 9. Institute of Medicine. Immunization Safety Review: Hepatitis B Vaccine and Demyelinating Neurological Disorders. Washington, DC: National Academies Press 2002.
• 10. CDC. Sentinel Counties Study of Viral Hepatitis (1992-1993, unpublished data)
• 11. CDC, National Immunization Program (NIP). (2004). Hepatitis B. In Epidemiology and prevention of vaccine-preventable diseases (“The Pink Book”) (8th ed.). Atlanta: Author.
• 12. Shapiro CN, McCaig LF, Gensheimer KF, et al (1989). Hepatitis B virus transmission between children in day care. Pediatric Infectious Diseases Journal 8:870-875.
• 13. Oleske J, Minnefor A, Cooper R Jr, et al (1980). Transmission of hepatitis B in a classroom setting. Journal of Pediatrics 97:770-772.
• 14. Daseda CC, Shapiro CN, Carroll K, et al. (1994). Hepatitis B virus transmission between a child and staff member at a day-care center. Pediatr Infect Dis J13; 828-30.