How Hepatitis B Is Transmitted

The hepatitis B virus is transmitted when blood, semen, or another bodily fluid from an infected person enters the body of another individual. The virus is extremely infectious—50 to 100 times more so than HIV.

The hepatitis B virus causes hepatitis B, a form of liver infection. There are many ways the virus can be transmitted, including the following.

Sexual Contact

Having unprotected sex with someone who is infected is the single most common way hepatitis B is transmitted in the U.S. and in other developed countries. Almost two-thirds of hepatitis B infections in the U.S. are spread through some form of sexual contact. In addition to blood, the virus has been found in semen and in vaginal fluids.

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-to-Infant Transmission

In countries with high rates of hepatitis B, mother-to-infant transmission (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 a chronic infection than people infected in adulthood. However, if proper medical care is available, effective preventive measures (the hepatitis B vaccine and hepatitis B immune globulin) can thwart most childhood infections.

Household Contact

Living with someone who has chronic hepatitis B increases the risk of getting infected. Some of this risk is probably due to 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.

How to Prevent Transmission

Between 2% and 6% of adults infected with hepatitis B virus will develop chronic hepatitis B. Chronic hepatitis B can lead to liver failure and liver cancer, so protecting yourself is important. The Centers for Disease Control and Prevention recommends all adults get screened for hepatitis B at least once.

The hepatitis B vaccine is safe for almost everyone and about 95% effective for providing long-term protection against hepatitis B infection.

While anyone can benefit from the vaccine, people who are at a greater risk of being exposed to the virus—because of their work, lifestyle or medical history—are strongly encouraged to be immunized. In many countries, babies born to infected mothers get vaccinated at birth. All babies born in the United States are routinely vaccinated.

Hepatitis B immune globulin (HBIG), is another way to prevent hepatitis B infection in babies born to infected mothers or after exposure to the virus. This uses concentrated antibodies to provide immediate protection. It is given as a shot and can provide short-term protection against hepatitis B.

Because the hepatitis B vaccine does not protect against HIV, hepatitis C or other diseases spread through sex and contact with blood, it is 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.