What is the risk of hepatitis B (HBV) transmission to a partner during sex in a patient with a low viral load and who is hepatitis B e-antigen (eAg) negative?

Risk of Hepatitis B Sexual Transmission with Low Viral Load and eAg-Negative Status

The risk of sexual transmission to your partner is substantially reduced but not zero when you are eAg-negative with low viral load, and your partner should be vaccinated immediately if not already immune—this is the single most effective protection strategy. 1

Understanding Your Transmission Risk Profile

Why eAg-Negative Status Matters

• eAg-negative carriers (also called "healthy" or "inactive" carriers) have significantly lower infectivity compared to eAg-positive individuals. 1
• eAg is a serologic marker of high viral replication—its absence indicates lower levels of circulating virus and reduced transmission potential. 1
• Your low viral load further decreases (but does not eliminate) the risk of transmitting HBV to sexual partners. 2

Quantifying the Risk to Your Partner

• Among susceptible heterosexual spouses of persons with chronic HBV infection, the seroprevalence of HBV infection ranges from 25% to 59% over time. 1
• However, this risk is substantially lower when the infected partner is eAg-negative with low viral load, as viral load directly correlates with transmission probability. 2
• One study found that HBV-infected individuals with HBsAg-positive sexual partners had significantly higher mean viral loads (3.9 log IU) compared to those with HBsAg-negative partners (2.8 log IU), suggesting lower viral loads reduce transmission risk. 2

Immediate Action Required: Partner Vaccination

The Most Critical Step

Your sexual partner must be tested for anti-HBs (hepatitis B surface antibody) and vaccinated immediately if susceptible—this provides 95% protection and is far more effective than any other preventive measure. 1

• The best single screening test for your partner is total anti-HBc (not IgM anti-HBc). 1
• If your partner is susceptible (negative for anti-HBs), vaccination should begin immediately using age-appropriate doses and schedules. 1
• Vaccination is the most effective precaution available and should be prioritized over all other interventions. 1

During the Vaccination Period

• Use barrier protection (condoms) during all sexual activity until your partner completes the vaccine series and develops documented immunity (anti-HBs positive). 1
• While the efficacy of latex condoms in preventing HBV infection is not definitively established, their proper use may reduce transmission risk. 1
• Sexual transmission occurs efficiently through both vaginal and anal intercourse, as semen and vaginal secretions contain infectious HBV. 3, 4

Essential Precautions to Prevent Transmission

Household Measures

• Do not share toothbrushes or razors, as these can become contaminated with blood. 1
• Cover all cuts or skin lesions to prevent spread of infectious secretions or blood. 1
• Clean any blood spills using detergents or bleach. 1
• HBV remains infectious on environmental surfaces for at least 7 days at room temperature. 3

What You CAN Safely Do

• Participate in all normal social activities, including sharing meals and utensils (spoons, forks, chopsticks). 1
• Kiss and hug others—casual contact does not transmit HBV. 1
• Breastfeeding is NOT contraindicated if you are female, as HBsAg in breast milk does not transmit infection when the infant receives appropriate prophylaxis. 3

Additional Restrictions

Medical and Donation Restrictions

• Do not donate blood, plasma, body organs, other tissue, or semen. 1
• Inform all healthcare providers and dentists of your HBsAg-positive status so they can take appropriate precautions. 1

Critical Clinical Pitfalls to Avoid

Common Misconceptions

• Even with low viral load and eAg-negative status, you remain potentially infectious—complete elimination of transmission risk only occurs when your partner develops vaccine-induced immunity. 1, 2
• Unprotected sex was not identified as the sole risk factor in some studies; cohabitation itself (sharing household items, close contact) was significantly associated with transmission. 2
• Female sexual partners appear to have higher susceptibility to infection compared to males. 2

Long-Term Monitoring

• You should have serial determinations of aminotransferases (ALT/AST) to monitor for progression to active hepatitis. 1
• Maintain abstinence from alcohol or very limited consumption, as alcohol significantly increases risks of cirrhosis and HCC in HBV carriers. 1
• Avoid smoking, which also increases risks of cirrhosis and HCC. 1