A person who is infected with HBV and the virus is not cleared from the body after 6 months is called chronically infected with HBV. The younger the infection, the more likely it is to cause chronic hepatitis B. In newborns, 90% of HBV infections will develop into chronic infections, and in infants and young children, about 25-30% of HBV infections will develop into chronic HBV infections. Only 5-10% of adolescent and adult-onset HBV infections will develop into chronic.