Incidence and Risk Factors for Acute Hepatitis B in the United States, 1982-1998: Implications for Vaccination Programs

In 1982, a safe and effective vaccine became available to prevent hepatitis B virus (HBV) infection and was recommended for persons at increased risk for infection. In 1991, a comprehensive immunization strategy was adopted that included routine childhood immunization and, in 1995, adolescent immunization. Since 1982, the CDC has conducted intensive sentinel surveillance of acute viral hepatitis in four US counties -- Jefferson County (Birmingham), Ala.; Denver County (Denver), Colo.; Pinellas County (St. Petersburg), Fla.; and Pierce County (Tacoma), Washington -- typical of the country with respect to disease incidence and demographic makeup. Researchers examined changes in disease incidence and risk factors for acute HBV during 1982-1998, and identified gaps in national immunization programs.

Between 1982 and 1998, 3,937 cases of acute HBV were reported. These accounted for 34 percent of all reported cases of acute viral hepatitis in the four counties. The median age of patients increased from 27 years (range, The highest incidence occurred in 1987 (13.8 cases per 100,000 population) and declined by 76.1 percent to 3.3 per 100,000 in 1998 (P <.001). Most of the decline occurred during 1987-1993. The decline of HBV incidence was observed in all four counties, in all age groups. The greatest decline occurred among persons 10-19 years old (72.5 percent [probably due to childhood and adolescent immunization]), followed by those 20-29 years old (70.6 percent) and 30-39 years old (53.4 percent) (P <.001 for each age group, 1982-1988 vs. 1994-1998). Average incidence decreased among whites by 70 percent, blacks by 47.7 percent, and Hispanics by 58.6 percent. Rates of disease were higher among males (range, 4.1-19.6 per 100,000) than females (range, 2.5-11.1 per 100,000).

A commonly recognized risk factor for infection during the exposure period was consistently identified for 66 percent (3,296) of subjects interviewed. Heterosexual exposure to an infected partner or to multiple partners (27.4 percent), IDU (18.2 percent), and MSM activity (13.5 percent) were the predominant risk factors, accounting for 88.3 percent of cases where risk could be identified.

During 1988-1998, a 90.6 percent decline in cases associated with IDU was observed, while the age of these patients increased significantly; blacks accounted for proportionately fewer cases during 1989-1998. Decline of HBV among IDUs was attributed by the authors to a reduction of the reservoir for infection due to death associated with HIV, or incarceration for drug-related offenses. During 1982-1986, a 63.5 percent decline occurred in cases associated with MSM, and remained static. This was temporally associated with a decline in high-risk sexual practices in response to the AIDS epidemic, but it was not sustained; MSM with acute HBV reported 1994-1998 were significantly older, with an increasing proportion of black and Hispanic MSM. A 50.7 percent decline occurred 1992-1994 among cases associated with high-risk heterosexual activity; new cases in 1994-1998 involved significantly older patients than before; declines occurred only among whites, whereas the absolute number and proportion of cases among blacks increased; 36.7 percent were exposed to a known infected partner, and 63.3 percent to multiple partners.

Of the 236 patients interviewed since 1996, when lifetime history of both STDs and incarceration was collected, 84 (35.6 percent) reported prior treatment for an STD and 68 (28.8 percent) reported incarceration. In all, 110 (46.6 percent reported one of these factors, and 21 (8.9 percent) reported both.

The authors identified two missed opportunities for HBV vaccination: in STD clinics and correctional facilities, which had the potential to prevent about one-half of new infections. Appropriate pre- or post-exposure immunization could have prevented most of the cases acquired from a known infected sex or household contact. Lack of reimbursement for vaccine purchase is a significant barrier to adult immunization. HBV cannot be eliminated until there is a nationwide program to vaccinate adults at increased risk for HBV, researchers concluded.

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