According to the Centers for Disease Control and Prevention (CDC), the rate of acute hepatitis B virus infection in the U.S. has declined by more than 80 percent since 1990, when routine hepatitis B vaccination of babies was implemented. While this is certainly good news, there are still about a million people in the U.S. today who suffer from chronic hepatitis B virus infection.
It is also important to know that the likelihood of acute hepatitis B
infection becoming chronic is higher the younger a person is when
infected. Approximately 90 percent of infants who are infected will
develop chronic infection; worldwide, most people with chronic hepatitis
B were infected at birth or during early childhood.
- See more at: http://blog.aids.gov/2013/08/the-end-of-hepatitis-b-transmission-begins-at-birth.html#sthash.RSF2mmUu.dpuf