Hepatitis B Incidence, July 11, 1986

Hepatitis B Incidence, July 11, 1986

According to a national survey in 1979, the HBV infection rate ranged from 31.1% to 61.6%, with an HBsAg carrier rate of 3.8% to 16.8%, averaging 8.8%. The HBsAg positivity rate gradually increases after birth, exceeding 30.4% before age 10, then declines with age. HBV infection occurs in three ways: first, through blood transfusions and blood products; second, through horizontal transmission—commonly referred to as contact transmission, involving general contact among the population, such as transmission via water, hands, or flies. This type of transmission accounts for about 55% of all cases, fortunately, adults can clear 30% of this type of infection themselves; third, through vertical transmission, especially mother-to-child transmission. The mother-to-child transmission rate for HBeAg-positive patients is 90%, and fathers carrying HBsAg can also transmit it at a rate of 20%. Once HBV enters the adult stage through vertical transmission, it cannot be cleared, unlike horizontal transmission, where 85% to 100% can become HBsAg carriers. Vertical transmission accounts for 40% of all cases, making it the main mode of HBV transmission in China.