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Hepatitis B and sexual activity

If hepatitis B is sexually transmitted, why doesn’t my spouse or partner have it? 

Hepatitis is spread through blood, semen and other bodily fluids and can be contracted through unprotected sexual contact with someone who has the virus. However transmission depends on the type of sexual activity and the viral load (HBV DNA) of the infected partner. 

Bodily fluids 

Semen, vaginal fluids and blood all contain the hepatitis B virus (HBV). The higher the viral load, the more infectious these fluids are. However, having a low viral load doesn’t mean you won’t infect someone during unprotected sexual intercourse. A man with an undetectable viral load, for example, can still spread infection as his semen will contain HBV. 

In heterosexual relationships, women are at higher risk of infection through unprotected sex than men, because they’re on the receiving end of semen. A man having unprotected sex with a woman with hepatitis B is at risk through contact with vaginal secretions, but the risk is lower.  

Types of sexual activity 

Some sexual activities come with a higher risk of hepatitis B transmission. Anal sex, for example, carries a very high risk due to tears in the skin that can occur during penetration, while oral sex can have a lower rate of hepatitis B transmission than vaginal sex. 


Hepatitis B is often considered a silent infection, because many people with the virus have no symptoms and may not know they have it.  

Getting tested 

Since 1988, New Zealand has offered hepatitis B vaccination to all babies. As a result, hepatitis B is rare in New Zealanders aged under 30. However, testing and a vaccination should still be offered to the household contacts and sexual partners of people who have hepatitis B.  

There is currently no cure for hepatitis B and long-term monitoring is important for people with the virus; this includes vital six-monthly blood tests to assess the state of the liver. Research is underway to find a cure. 


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