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How Hepatitis B Spreads

Four Ways Hepatitis B Spreads


Updated April 29, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

The hepatitis B virus spreads when blood, semen, or another bodily fluid from an infected person enters the body of another individual. Since the virus is extremely infectious -- 50 to 100 times more so than HIV -- even brief, direct contact could be enough to cause infection.

There are many ways hepatitis B can spread, including:

Sexual Contact

Having unprotected sex with someone infected is the single most common way hepatitis B spreads in the United States and in other developed countries. In addition to blood, the virus has been found in semen and vaginal fluids. Almost two-thirds of hepatitis B infections in the United States are spread through some form of sexual contact. Even kissing can spread hepatitis B, though this is very uncommon.

Injection Drug Use

Drug users who share syringes and drug equipment have an increased risk of getting infected. It's estimated that around 16% of new hepatitis B infections are from IV drug use. This risk of infection increases the longer someone abuses injection drugs.

Mother-Infant Transmission

In countries with high rates of hepatitis B, mother-infant spread (also called vertical or perinatal transmission) is a major cause of new infections. Some places have a tremendous public health problem because a significant number of mothers infect their babies, and those babies have a greater chance of developing chronic infection than people infected in adulthood. However, if proper medical care is available, effective preventive measures(vaccine and HBIG) can thwart most childhood infections.

Household Contact

Living with someone who has chronic hepatitis B increases the risk of getting infected. Some of this is probably because of the sharing of certain household items. Anything that could contain infected blood and bodily fluid has the potential for spreading the hepatitis B virus. Because the virus can live outside the body for a period of time, certain items like razors, toothbrushes and nail clippers are possible vehicles for transmission.

Preventing Infection

The hepatitis B vaccine is a safe and effective way (for about 9 out of 10 people) to have long-term protection against hepatitis B infection. Chronic hepatitis B can lead to liver failure and liver cancer, so protecting yourself is important. While anyone can benefit from the vaccine, people who -- through their work, lifestyle or medical history -- are at a greater risk of being exposed to the virus are strongly encouraged to be immunized. However, since hepatitis B vaccine will not protect against HIV, hepatitis C or other diseases spread through sex and contact with blood, it's still important to keep using basic protective strategies. Practicing safer sex and not sharing needles are recommended -- even if you're immune to hepatitis B.

Immune globulin, specifically HbIG, is another way to prevent hepatitis B infection. This uses concentrated antibodies to provide immediate protection.

In many countries, children are immunized from infancy because they were infected at birth or because they benefited from a childhood hepatitis B vaccination program.


Centers for Disease Control and Prevention. Hepatitis B Transmission and Exposure. Accessed October 25, 2009.

National Digestive Diseases Information Clearinghouse. What I Need to Know About Hepatitis B. Accessed October 25, 2009.

Teo E, Lok A. Epidemiology, Transmission and Prevention of Hepatitis B Virus Infection. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2009.

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