Objective: To estimate the number of hepatitis B virus (HBV) infections among US children younger than 10 years before implementation of routine childhood hepatitis B immunization.
Methods: Incidence of HBV infection in children was modeled from existing prevalence data by means of regression analysis. Sources of data for the models included published and unpublished surveys that determined the prevalence of HBV infection in US-born children. The number of nonperinatal HBV infections in children younger than 10 years was estimated by applying these infection rates to 1991 population data according to maternal race, ethnicity, and birthplace.
Results: Estimated annual rates of infection ranged from 24 per 100 000 in non-Asian children to 2580 per 100 000 in children of Southeast Asian immigrant mothers. These rates indicate that by the early 1990s, HBV was infecting 16 000 children who were younger than 10 years (8700 non-Asian children and 7300 Asian-American children) annually. The total estimate, not including perinatal infections, ranged from 12 000 (95% confidence interval: 5500-27 700) to 24 900 (95% confidence interval: 16 700-42 300) infections and depended on how the estimated rates were applied to the population data.
Conclusion: Thousands of US children were infected each year with HBV before routine infant hepatitis B immunization, placing them at high risk of death from cirrhosis or hepatocellular carcinoma later in life.