This question is a common one. Hepatitis B is indeed easily transmitted sexually, so why do some people — who were not vaccinated — never get hepatitis B from their sexual partners? It comes down to variables, such as:
- The type of sexual activity you engage in
- The viral load (HBV DNA) of the infected partner and
- Who is on the receiving end of infectious body fluids, especially blood that contains the most virus and semen.
Having one partner infected, and other not, can add more stress to an already traumatic hepatitis B diagnosis.
Let’s now discuss the factors that affect who gets infected and who doesn’t when two people have sex.
Semen, vaginal fluids and blood all contain the hepatitis B virus (HBV), and the higher the viral load, the more infectious one’s blood and body fluids are.
THE ROLE OF GENDER
In heterosexual relationships (between man and woman), uninfected women are at higher risk of getting infected by a male partner infected with hepatitis B, than the reverse. Women are on the receiving end of semen, which greatly increases their risk of becoming infected unless a condom is used.
When a woman is infected with hepatitis B, an uninfected man is at risk through direct contact with her vaginal secretions, but that contact is lower-risk than a woman’s direct exposure to infectious semen during intercourse.
However, an infected woman who is menstruating is more likely to spread hepatitis B because blood can contain higher levels of HBV than vaginal secretions. That is why gloves and dental dams are recommended to provide a barrier against exposure.
The “uninfected” partner could already have been infected and cleared hepatitis B: When a person is first diagnosed with hepatitis B, doctors often test his or her partner for only the hepatitis B surface antigen (HBsAg), which indicates a current hepatitis B infection. If they are negative for HBsAg, they are immediately vaccinated.
If the partner isn’t also tested for the hepatitis B surface antibody (anti-HBs or HBsAb), then no one knows if the individual was infected years ago (or earlier in the relationship) with hepatitis B and cleared the acute infection.
Hepatitis B is not called the “silent” infection for nothing — many people who get hepatitis B never have any symptoms and never realize they were infected. As a result, a wife, husband, partner or lover who tested negative for HBsAg, may actually have been infected in the past and cleared the infection and now has protective hepatitis B surface antibodies to forever safeguard them from infection. If they’re immediately vaccinated and retested after the three-dose vaccination, they will test positive for surface antibodies, without ever knowing that their antibodies resulted from a past infection, not immunization.