Hepatitis B is caused by a virus spread through contact with blood or bodily fluids of an infected person. This includes mother-to-child transmission. Approximately 43,000 people per year are infected in the United States and 1.25 million people in the US are chronically infected with hepatitis B. Some people recover completely while for others it becomes a chronic infection. For more information on Hepatitis B in children and the Hepatitis B vaccine, download the GIKids Fact Sheet on Hepatitis B.