Effects of Universal Vaccination for Hepatitis B

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The summary below is from the full report titled "Hepatitis B Virus Infection in Children and Adolescents in a Hyperendemic Area: 15 Years after Mass Hepatitis B Vaccination." It is in the 6 November 2001 issue of Annals of Internal Medicine (volume 135, pages 796-800). The authors are Y-H Ni, M-H Chang, L-M Huang, H-L Chen, H-Y Hsu, T-Y Chiu, K-S Tsai, and D-S Chen.

What is the problem and what is known about it so far?

Hepatitis B is an inflammation of the liver caused by a virus. The virus spreads from person to person through contact with infected body fluids. For example, the virus can be spread through sexual intercourse or contaminated needles or blood or from mother to baby at birth. Most people with hepatitis B recover within a few months, but some develop chronic inflammation, permanent scarring (cirrhosis), or liver cancer. Vaccines that contain small amounts of dead or altered virus can boost the body's normal defense (immune) system and help prevent hepatitis B and related complications. Taiwan has had very high rates of hepatitis B. In the mid-1980s, Taiwan began a program of universal hepatitis B vaccination for newborns, school children, teenagers, and young adults. This study describes the success of that program.

Why did the researchers do this particular study?

To describe the effects of a universal vaccination program against hepatitis B in Taiwan.

Who was studied?

1357 persons younger than 15 years of age who were born after the vaccination program began and 559 persons 15 to 20 years of age who were born before the program began.

How was the study done?

Study participants were recruited from well-baby clinics and schools in a single district of Taipei City. They gave blood samples that were tested for evidence of hepatitis B. The researchers compared markers of past infection (antibodies to the hepatitis virus called anti-HBc) and markers of a chronic infectious or carrier state (hepatitis surface antigen, called HbsAg) between people born before and those born after the vaccination program began.

What did the researchers find?

Approximately 20% of participants born before the vaccination program had evidence of hepatitis B (anti-HBc) compared with 3% of those born later. About 10% of participants born before the vaccination program were chronic carriers of hepatitis B virus (HBsAg-positive) compared with less than 1% of those born since the program began.

What were the limitations of the study?

Taiwan has had very high rates of hepatitis B, and at least 80% of children and young adults have been vaccinated under this universal program. Vaccine programs may be less effective in places where hepatitis B is uncommon or if less than 80% of the target population actually gets vaccinated.

What are the implications of the study?

Universal vaccination of children and young adults can significantly decrease hepatitis B and chronic carrier states.