Hepatitis B is a vaccine-preventable, communicable disease of the liver caused by HBV. HBV is transmitted through percutaneous (i.e., puncture through the skin) or mucosal (i.e., direct contact with mucous membranes) exposure to infectious blood or body fluids. Since HepB vaccine was introduced in 1982, the number of reported hepatitis B cases has declined substantially. However, despite reductions in hepatitis B incidence during the past 4 decades, which were achieved through incremental expansion of groups for whom HepB vaccination is recommended, progress in recent years on further reducing acute hepatitis B cases has stalled (). Incident hepatitis B declined from 26,654 reported cases (172,700 estimated actual cases) in 1985 to a low of 2,791 reported cases (18,100 estimated actual cases) in 2014 (,). In 2019, a total of 3,192 cases of acute hepatitis B were reported to CDC, corresponding to 20,700 estimated acute infections (95% CI = 11,800–50,800). The most commonly reported risk behaviors and exposures were injection drug use (35%), multiple sex partners (23%), and surgery (10%), followed by other sexual and bloodborne risk behaviors; risk behavior and exposure information were missing for 37.1% of cases. There are an estimated 880,000 (95% CI = 580,000–1,170,000) prevalent chronic HBV infections in the United States based on 2013–2018 National Health and Nutrition Examination Survey data, with a modeled estimate of 1.89 million (range = 1.49–2.40 million) that accounts for potential underrepresentation of the non-U.S.–born population (,). In 2018, the reported HepB vaccination coverage (≥3 doses) was 30.0% among adults aged ≥19 years, only a small increase over the past 4 decades ().

Background And Aims: Although prevalence of chronic hepatitis B (CHB) in the USA includes 0.42 million (range, 0.28-0.67) U.S.-born persons, foreign-born (FB) persons contribute a substantially larger number to the burden of CHB in the USA. Over the past decade, patterns of U.S. immigration have changed and many countries have implemented HBV prevention programs. This study aims to estimate the number of FB persons with CHB in the USA by country of origin, updating our 2011 study.

Approach And Results: We performed systematic searches for articles published in 2009-2019 reporting HBsAg seroprevalence in emigrants and in-country populations of 117 countries. Data meeting inclusion criteria were combined with data from our 2011 study to calculate pooled prevalence estimates for 99 countries using meta-analyses (total 2,800 surveys involving 112 million subjects). Combining country-specific CHB rate estimates with the number of FB in the USA in 2018, by country of origin from the U.S. Census Bureau, we estimate that the number of FB with CHB in the USA in 2018 was 1.47 million (95% CI, 1.21-1.73), substantially higher than previously reported. The weighted average CHB prevalence for all FB in the USA in 2018 was 3.07%. Approximately 59% of FB with CHB in the USA in 2018 emigrated from Asia, 19% from the Americas, and 15% from Africa. Subgroup analyses found that for many countries, CHB rates are higher in males than females and have declined over the past three decades, but no consistent pattern is observed between emigrant and in-country rates.

Conclusions: Including FB and U.S.-born persons, the total prevalence of CHB in the USA may be as high as 2.4 million.

Between 800,000 and 1.8 million people in the United States and >290 million people worldwide are infected with hepatitis B virus (HBV), which can lead to hepatitis B, a vaccine-preventable communicable disease. The estimated prevalence of chronic hepatitis B infection among pregnant women in the United States is 0.7% to 0.9%, with >25,000 infants born annually at risk for chronic infection. Although transmission through sexual intercourse and intravenous drug use are major risk factors for acquisition of HBV among adults in the United States, perinatal transmission is responsible for up to 50% of HBV infections worldwide. Approximately two-thirds of people with hepatitis B are unaware of their infection. The risks of acquiring hepatitis B may be unrecognized. Updated recommendations call for universal hepatitis B screening during pregnancy and in adults aged ≥18 years, and universal vaccination through the age of 59 years, given that anyone can be infected with HBV.
In contrast to HBV acquisition in adulthood, which more commonly leads to resolution of acute infection and lifelong immunity, perinatal HBV is more likely to lead to chronic infection and associated long-term sequelae. Chronic hepatitis B infection will develop in up to 90% of perinatally exposed neonates who do not receive appropriate immunoprophylaxis, in contrast to 10% to 25% of infected children and 5% to 10% of exposed immunocompetent adults. Among all individuals with chronic HBV infection, regardless of the timing of infection, 20% will eventually die of complications of HBV infection, including cirrhosis, end-stage liver disease, and hepatocellular carcinoma. Chronic HBV infection is the major source of hepatocellular carcinoma globally, leading to 50% of cases worldwide and 80% of cases in high-endemic areas. An estimated 2.4 million people in the United States have chronic hepatitis B, with persons of Asian or African descent being disproportionately affected. Rates of acute hepatitis B are known to vary by race and ethnicity.

Chronic hepatitis B virus (HBV) infection represents a major global health problem, affecting an estimated 257-291 million persons worldwide and is associated with substantial morbidity and mortality because of clinical complications, such as liver cirrhosis and hepatocellular carcinoma. Despite existing resources for vaccination, screening, and treatment, the burden of chronic HBV remains significant within the United States (US). Both the World Health Organization (WHO) and US Department of Health and Human Services (DHHS) have articulated formal hepatitis elimination plans, although an updated assessment of the epidemiology and prevalence of chronic HBV is needed to inform these initiatives. The Chronic Liver Disease Foundation (CLDF), a nonprofit 501(c)(3) educational organization dedicated to raising awareness of liver disease, partnered with a panel of leading US hepatologists to conduct an updated literature review to develop a contemporary HBV prevalence range estimate. Panel members researched and evaluated the peer-reviewed literature on HBV prevalence and, in May 2019, discussed their findings during a live HBV epidemiology workshop. The panel proposed an overall estimated prevalence for chronic HBV infection in the US of 1.59 million persons (range 1.25-2.49 million). This review provides a summary of the workshop findings and conclusions, which may serve to inform future initiatives focused on HBV screening and prevention in the US.

The risk for HBV infection varies substantially by country of origin in non–US-born persons living in the US. Persons born in countries with a prevalence of hepatitis B surface antigen (HBsAg) of 2% or greater (Table 2, Figure 2) account for the majority of cases of new chronic HBV infection in the US; most persons in these countries acquired HBV infection from perinatal transmission.2Persons born in the US with parents from regions with higher prevalence are also at increased risk of HBV infection during birth or early childhood, particularly if they do not receive appropriate passive and active immunoprophylaxis (and antiviral therapy for pregnant women with a high viral load) (Figure 2).11-13The CDC classifies HBV endemicity levels by prevalence of positive HBsAg (high [8%], moderate [2%-7%], or low [<2%]) (Figure 2). The estimated prevalence of HBV infection in the general US population is 0.3% to 0.5%,8,9,11,12,14,15which makes it reasonable to screen adolescents and adults born in countries or regions with an HBsAg prevalence of 2% or greater (regardless of vaccination history in their country of origin) and adolescents and adults born in the US who did not receive the HBV vaccine as infants and whose parents were born in regions with an HBsAg prevalence of 8% or greater (regardless of their biological mother’s HBsAg status).
Quiz Ref IDHBV screening should also be offered to other risk groups defined by clinical and behavioral characteristics in which prevalence of positive HBsAg is 2% or greater. Persons from such risk groups include persons who have injected drugs in the past or currently; men who have sex with men; persons with HIV; and sex partners, needle-sharing contacts, and household contacts of persons known to be HBsAg positive2,3,9,12-14,16,17(Table 3).

The overall prevalence of chronic hepatitis B virus (HBV) infection in the US was been estimated at about 0.3% in 2007 to 2012, or approximately 847 000 persons. People born in countries with a 2% or greater HBV prevalence accounted for 47% of chronic infections in the US, based on survey data published through 2010, and for 95% of chronic infections in the US, based on an analysis of cases during 1974 to 2008. Since 2010, an increase in acute and chronic HBV infection related to drug use in younger adults has been reported in several states.

In 2014, the US Preventive Services Task Force (USPSTF) recommended screening for HBV infection in persons at high risk for infection (B recommendation); an HBV prevalence of 2% or greater was noted as a reasonable threshold for deciding to screen. This evidence report was conducted to update the 2014 review on HBV screening to inform the USPSTF for an updated recommendation statement.

Hepatitis B vaccines have been available in the United States since 1981. Multiple formulations (Recombivax HB and Comvax, Merck; Engerix-B, Pediatrix, and Twinrix, GlaxoSmithKline) are now licensed in the United States (Table 1); all are produced with the use of yeast (Saccharomyces cerevisiae) and recombinant techniques to generate the hepatitis B surface antigen (HBsAg) protein.

In 1991, the Advisory Committee on Immunization Practices (ACIP) recommended a comprehensive strategy to eliminate HBV transmission in the United States, which included universal vaccination of infants. In 1995, routine immunization of adolescents was added. In 1999, the strategy was further modified to include immunization of all persons up to 18 years of age. This strategy has reduced the overall annual incidence of acute HBV infections in the United States (from 8.5 cases per 100,000 persons in 1990 to 2.8 per 100,000 in 2002, a decrease of 67 percent).

On the basis of data indicating a decrease in the burden of acute (and hence chronic) HBV infection as a result of immunization programs for infants, children, and adolescents, the World Health Organization (WHO) has recommended that all countries provide universal HBV immunization programs for infants and adolescents. As of 2003, 79 percent of the 192 WHO member states had adopted policies of universal childhood immunization against HBV., One compelling example of the associated benefit is the dramatic decline in the incidence of neonatal HBV infections and subsequent sequelae in Taiwan after the introduction and widespread use of hepatitis B vaccine.–

Since 1991, the Occupational Safety and Health Administration has mandated that health care workers be educated about the vaccine and that employers offer it free of charge. Except for pregnant women, routine screening for HBsAg or for antibodies to HBsAg (anti-HBs antibodies) is not routinely recommended; whether or not to screen is a clinical decision that should be based on the likelihood of previous exposure to HBV or hepatitis B vaccine.

Table 1:
Caption: Dosing Schedule for Recombivax HB, Engerix-B, and Twinrix Hepatitis B Vaccines.

Patterns of transmission, including the route and age at acquisition of HBV, differ in different parts of the world. In areas such as Southeast Asia and among immigrants from that region to the United States, in whom HBV infection is highly endemic (defined as a prevalence of chronic HBV infection of 8 percent or greater), perinatal transmission and acquisition of HBV in the first five years of life are common. In contrast, in areas of low endemicity (defined by a prevalence of chronic HBV infection of less than 2 percent), such as the United States, most infections are acquired in adolescence or adulthood through sexual contact, parenteral drug use, household contact with a chronic HBV carrier or a person with acute infection, or occupational exposure. Although 8 percent of HBV infections in the United States are estimated to occur among infants and children, these cases represent approximately 36 percent of chronic infections and thus constitute a substantial reservoir of HBV and account for considerable morbidity and mortality. Furthermore, no risk factor can be identified in one third or more of patients with hepatitis B. Universal immunization will overcome many of these limitations.

Universal immunization of infants will be cost effective because the medical costs of acute and chronic HBV disease are high and because a lower dose of vaccine can be given to infants and children less than 11 years of age.,, Depending on the vaccine product, only one quarter (0.25 ml) or one half (0.5 ml) of the dose given to adults (1.0 ml) is recommended for the routine immunization of children. The cost per dose is thus similar to that of the other routinely recommended childhood vaccines.

The three-dose schedule for primary immunization against HBV should be begun in early infancy. The American Academy of Pediatrics recommends giving the first dose before discharge from the hospital after delivery; the second dose should be administered at 1 to 2 months of age, followed by a third dose at 6 to 18 months of age. This schedule minimizes the need to give multiple injections during the same visit. An alternative schedule, provided the mother is not infected with HBV (that is, is negative on serologic testing for hepatitis B surface antigen [HBsAg]), is for vaccine at 1 to 2, 4, and 6 to 18 months of age.