Hepatitis B Basic Information
Hepatitis B is a liver infection caused by the hepatitis B virus (HBV). Hepatitis B is transmitted when blood, semen, or another body fluid from a person infected with the HBV virus enters the body of someone who is not infected. This can happen through sexual contact; sharing needles, syringes, or other drug-injection equipment; or from mother to baby at birth. For some people, HBV is an acute, or short-term, illness but for others, it can become a long-term, chronic infection. Risk for chronic infection is related to age at infection: approximately 90% of infected infants become chronically infected, compared with 2%–6% of adults. Chronic HBV can lead to serious health issues, like cirrhosis or liver cancer. The best way to prevent HBV is by getting vaccinated.
In the United States, an estimated 850,000 - 2.2 million persons are chronically infected with the hepatitis B virus. New cases of HBV infection in the United States had been decreasing until recently. In 2013, there were an estimated 19,800 acute cases of HBV infection. That is an increase of over 5% compared to 2012. This is the first time in more than 20 years that acute HBV cases increased. This increase in new HBV infections is a very concerning trend which The Centers for Disease Control and Prevention has determined is linked to the ongoing opioid abuse epidemic in the United States.
Globally, HBV is the most common blood-borne infection with an estimated 240 million people chronically infected according to the World Health Organization.
In the U.S., rates of new HBV infection are highest among adults ages 30-49 years of age, reflecting low hepatitis B vaccination coverage among adults at risk. The most common risk factor among people with new HBV infections was injecting drugs, related to the opioid abuse epidemic.
The highest rates of chronic hepatitis B infection in the United States occur among foreign born individuals, especially people born in Asia, the Pacific Islands, and Africa. Over half of cases in the US are among people who were born outside of the United States. CDC developed this map of the geographic distribution of hepatitis B around the world. Other groups who have higher rates of chronic HBV infection include people who inject drugs and men who have sex with men.
HBV infection is fairly common among people living with HIV. About 10 percent are coinfected with HBV reflecting the shared modes of transmission for these two infections. People living with HIV are at greater risk for complications and death from HBV. All people with HIV are recommended to be tested for HBV and if susceptible, are further recommended to receive the HBV vaccination or, if chronically infected, evaluated for treatment to prevent liver disease and liver cancer. For more information about HIV and HBV coinfection, visit AIDS.gov’s pages about hepatitis B and HIV coinfection.
Hepatitis B is spread in several distinct ways: sexual contact; sharing needles, syringes, or other drug-injection equipment; or from mother to baby at birth.
In the U.S. in 2013, injection drug use was the most common risk factor among people with an acute HBV infection, followed by sexual contact with a person with HBV infection. Less commonly reported risk factors included accidental needle sticks, surgery, transfusions, and household contact with a person with HBV. In the United States, healthcare related transmission of HBV is rare.
Mother-to-child transmission of HBV is especially concerning, because it is preventable. About 1,000 mothers transmit HBV to their infants each year in the United States. Tragically 90 percent of HBV-infected newborns will develop chronic infection, remaining infected throughout their lives, and up to 25 percent of people infected at birth will die prematurely of HBV-related causes. For this reason, the standard of care for pregnant women includes an HBV test during each pregnancy so that the appropriate steps can be taken to prevent HBV-positive mothers from transmitting the disease to her infant.
Globally, mother-to-child transmission and inadequate infection control in health care settings represent significant modes of viral hepatitis transmission. That is why immigrants from many countries are recommended to be tested for HBV as well as hepatitis C virus (HCV).
Hepatitis B is a vaccine-preventable disease. The hepatitis B vaccine is safe and effective and is usually given as 3-4 shots over a 6-month period starting at birth. Immunization programs for infants and adolescents that started in 1991 have resulted in substantial declines in the incidence of HBV infection in young people. Find out if you should get the hepatitis B vaccine. Also, the Hepatitis B vaccine is a covered preventive service under many health plans.
Hepatitis B can also be prevented by avoiding contact with contaminated blood and unprotected sexual exposure. Using condoms has also been shown to reduce the chance of sexually transmitted infections.
Mother-to-child HBV transmission can be prevented by identifying pregnant women who are chronically infected and providing the hepatitis B vaccine and hepatitis B immunoglobulin at birth. Recently updated guidelines also recommend that pregnant women with chronic HBV be referred to a specialist and considered for HBV treatment to further reduce the chance of transmitting the virus.
The CDC estimates that half of people with chronic HBV are unaware of their infection. The only way to find out if you have a hepatitis B infection is to get an HBV test. All it takes is a simple blood test. Being aware of your hepatitis B status is important because treatments are available that reduce the chance of developing liver disease and liver cancer. You can also protect your family members by getting them vaccinated. Also, Hepatitis B testing is a covered preventive service under many health plans.
The following populations are at increased risk of becoming infected with HBV and are recommended to be tested:
- Infants born to infected mothers
- Sex partners of infected persons
- Sexually active persons who are not in a long-term, mutually monogamous relationship (e.g., >1 sex partner during the previous 6 months)
- Men who have sex with men
- Injection drug users
- Household contacts of persons with chronic HBV infection
- Health care and public safety workers at risk for occupational exposure to blood or blood-contaminated body fluids
- Hemodialysis patients
- Residents and staff of facilities for developmentally disabled persons
- Travelers to countries with intermediate or high prevalence of HBV infection
There are several antiviral treatments available for chronic HBV infection and everyone with chronic HBV should be linked to care, considered for treatment, and regularly checked for liver damage and liver cancer. Hepatitis B treatments reduce the amount of virus in the body and reduce the chance of developing serious liver disease and liver cancer. However, most people cannot be cured of HBV and treatment is recommended to continue for the rest of the person’s life. Research for more effective treatments and a cure for HBV is ongoing.
Know Hepatitis B- CDC’s Hepatitis B Education Campaign for Asian Americans, Pacific Islanders, and others at risk
Centers for Disease Control and Prevention, Division of Viral Hepatitis
National Institutes of Health:
- What do I need to know about Hepatitis B
- What Asians and Pacific Islanders need to know about Hepatitis B
HHS Office of Women’s Health
- Archived webinar, “What every Woman Needs to Know about Hepatitis B and C”