Approximately 30% of the global population has serologic evidence of achieving disease or prior HBV infection. half of all deaths due to liver cancer in 2010 were associated with HBV infection, and between 1990 and 2010, there was a 62% increase in liver cancer-related deaths and a 29% increase in cirrhosis-related deaths worldwide. HBV is transmitted through contact with infected blood or semen, and there are three main modes of transmission. In areas of high disease prevalence, the vast majority is mother-to-child transmission. In low endemic areas, sexual transmission is the main mode of transmission. People with multiple sexual partners, gay men and those who have had other sexually transmitted infections are at high risk for HBV infection. The third major route of transmission is unsafe injections, blood transfusions or dialysis. Although screening of blood products has been effective in reducing transfusion-associated HBV infections, this route of transmission is still relatively common in developing countries. Other possible routes of HBV transmission include nosocomial infections caused by transmission through infected medical, surgical, or dental instruments, needle-stick injuries, and organ donations from HBsAg-positive or HBV DNA-positive individuals. Family life, intimate contact or living in crowded conditions are also possible risk factors. The prognosis of acute HBV infection is age-related: >95% of newborns, 20-30% of children aged 1-5 years and <5% of adults will develop chronic infection. Globally, HBV vaccination of newborns has led to significant reductions in prevalence in many regions (Figure 1). However, vaccine efficacy rates vary widely by region: 90% in the Western Pacific and the United States, compared with 56% in South Africa. Half of all deaths from liver cancer in 2010 were associated with HBV infection, and between 1990 and 2010, there was a 62% increase in liver cancer-related deaths and a 29% increase in cirrhosis-related deaths worldwide. HBV is transmitted through contact with infected blood or semen, and there are three main modes of transmission. In areas of high disease prevalence, the vast majority is mother-to-child transmission. In low endemic areas, sexual transmission is the main mode of transmission. People with multiple sexual partners, gay men and those who have had other sexually transmitted infections are at high risk for HBV infection. The third major route of transmission is unsafe injections, blood transfusions or dialysis. Although screening of blood products has been effective in reducing transfusion-associated HBV infections, this route of transmission is still relatively common in developing countries. Other possible routes of HBV transmission include nosocomial infections caused by transmission through infected medical, surgical, or dental instruments, needle-stick injuries, and organ donations from HBsAg-positive or HBV DNA-positive individuals. Family life, intimate contact or living in crowded conditions are also possible risk factors. The prognosis of acute HBV infection is age-related: >95% of newborns, 20-30% of children aged 1-5 years and <5% of adults will develop chronic infection. Globally, HBV vaccination of newborns has led to significant reductions in prevalence in many regions (Figure 1). However, there are significant regional differences in vaccine efficacy: 90% in the Western Pacific and the United States, compared with 56% in South Africa. As a result, HBV prevalence also varies across the world: 45% of HBV-infected individuals live in areas with high disease prevalence (prevalence ≥8%): this includes China, South Asia, much of Africa, much of the Pacific Islands, parts of the Middle East, and the Amazon Basin, where infection is predominantly neonatal or childhood. Thanks to widespread vaccination of newborns, some countries with a high prevalence of the disease, such as China, which currently has an overall prevalence of 7-8%, are expected to move into the ranks of moderately endemic areas of the disease this year. More than 43% of HBV-infected patients live in moderately endemic regions (2%-7% prevalence): including Southwest Central Asia, Eastern Europe, Southern Europe, Russia, Central America, and South America. In these regions, there are multiple transmission routes including neonatal, pediatric, and adult. The remaining 12% of the infected population lives in low prevalence areas (<2% prevalence): including North America, Western Europe, Australia, and Japan. In these areas, the infection is primarily among adolescents or adults through sexual or unsafe injection routes. < p=""> Immigration has a significant impact on prevalence in high-income countries. a 2012 meta-analysis showed that the prevalence of HBV infection among immigrants or refugees was 7.2%, while the proportion of them who were immune was 39.7%. In the United States, approximately 95% of newly diagnosed chronic HBV infections are expected to be among immigrants.