The likelihood that infection becomes chronic depends upon the age at which a person becomes infected. Children less than 6 years of age who become infected with the hepatitis B virus are the most likely to develop chronic infections.
In infants and children:
80–90% of infants infected during the first year of life develop chronic infections; and
30–50% of children infected before the age of 6 years develop chronic infections.
less than 5% of otherwise healthy persons who are infected as adults will develop chronic infection; and
20–30% of adults who are chronically infected will develop cirrhosis and/or liver cancer.