Key Takeaways:
- Hepatitis B virus can be transmitted via sexual contact, birth, and breaks in the skin.
- Vaccination against hepatitis B is the most effective way to prevent infection and subsequent liver disease, with the first dose given shortly after birth.
- Immediate vaccination protects babies from perinatal HBV and transmission from household and community environments.
Hepatitis B vaccination remains a public health priority because approximately one-third of the world’s population (about two billion people) show evidence of current or past HBV infection. Importantly, many patients don’t know they are a carrier, putting any susceptible (unvaccinated) people, including infants, at risk.
What is hepatitis B virus (HBV)?
Communicable liver disease has been recognized for centuries, long before scientists identified the hepatitis viruses responsible. Interestingly, while each of the hepatitis viruses (A, B, C, D, and E) cause liver disease, they are genetically distinct and belong to different viral families. Hepatitis B is a DNA virus in the Hepadnaviridae family, while hepatitis A is an RNA picornavirus, hepatitis C is an RNA flavivirus, hepatitis D is an unclassified RNA virus, and hepatitis E is an RNA hepevirus.
HBV infection can cause a chronic liver infection that may be asymptomatic for years before developing into liver disease. When a susceptible adult is infected with hepatitis B virus, the infection is most often self-limited, and about 95 percent recover completely. However, for infants, the story is very different: nearly all babies infected with HBV develop lifelong chronic infection, which can progress to a variety of liver diseases later in life including cirrhosis, hepatic decompensation, and/or hepatocellular carcinoma (liver cancer).
How is hepatitis B virus (HBV) transmitted?
HBV most commonly spreads through exposure to certain body fluids either through sexual contact, perinatal transmission (during birth), or percutaneous exposure (cuts in the skin or sharing contaminated needles). Though HBV can be found in saliva, it is not transmitted by kissing or sharing utensils, nor is it spread through consumption of food, water, breastfeeding or through the air. Transmission in households and daycares is uncommon but does occur in areas with high prevalence of HBV. Due to screening protocols, transmission is rare with blood transfusion or organ transplantation. Similarly, universal infection control precautions have made patient-to-healthcare professional transmission uncommon.
How is hepatitis B virus (HBV) infection prevented?
Vaccination is the most effective way to prevent HBV infection. The American Academy of Pediatrics recommends hepatitis B vaccine for all newborns (first dose given within 24 hours after birth, followed by another dose at 1-2 months and a third at 6-18 months) and catch up vaccination as soon as it's identified for any unvaccinated children.
For households where someone has HBV, personal prevention measures should be implemented. Precautions include using barrier protection during sex, avoiding shared personal items such as toothbrushes and razors, covering cuts and scratches, and disinfecting blood spills with bleach.
Why is the first dose of hepatitis B vaccine recommended at birth?
Given that sexual and drug-related transmission of HBV is most common, why do newborns need immediate vaccination? There are two reasons. First, immunization within a day of life can prevent the hepatitis virus from taking hold via perinatal transmission during birth. Second, it can protect the newborn from household or community exposure after discharge.
Hepatitis B virus is highly infectious. It can survive on surfaces for up to a week and be transmitted to susceptible (unvaccinated) people even without visible blood. While billions of people have evidence of HBV infection, many don’t discover that they carry the virus until they develop liver issues later in life. This means babies can be exposed at birth or at home from family members who are unaware they’re infected.
Universal vaccination has not only reduced the incidence of HBV infection worldwide it has also reduced the incidence of HBV-associated complications including hepatocellular carcinoma. This is why the World Health Organization and the American Academy of Pediatrics recommend the hepatitis B vaccine birth dose for every newborn.
“With vaccines, waiting isn’t neutral. Delaying means missing the window when children are most vulnerable – and when the vaccine is most protective.”
“With vaccines, waiting isn’t neutral. Delaying means missing the window when children are most vulnerable – and when the vaccine is most protective.”
Why don’t we just screen pregnant individuals for hepatitis B?
We do screen pregnant individuals and HBV status is an important part of HBV prevention and newborn care. In fact, immunization recommendations differ based on maternal HBV status.
- HBV-positive (or unknown HBV status) pregnant individuals: Newborns receive the first vaccine dose within 12 hours of birth plus hepatitis B immunoglobulin (HBIG) for immediate protection. The HBIG antibodies start attacking the virus before the baby’s own B cells are primed from the vaccine. These infants are monitored and tested for HBV to ensure the immunizations worked.
- HBV-negative pregnant individuals: Newborns weighing at least 2,000 g (4.4 lb) receive HBV vaccination within 24 hours of birth. Premature neonates and those weighing less than 2,000 g receive the vaccine at one month or at hospital discharge, whichever is first. However, they do not receive HBIG.
Why vaccinate even when the pregnant person tests HBV negative?
First, screening is not perfect. False negatives happen, meaning that a person can carry the virus even though the test does not detect it. Second, pregnant individuals may be exposed to HBV between testing and giving birth, a window which can be months long. Finally household members are not screened, and babies can be exposed after birth. Perinatal transmission isn’t the only route of infection for vulnerable babies, who may be exposed to HBV from chronic carriers unaware of their infection.
Prior to routine vaccination at birth, up to half of HBV infections acquired in infancy were not attributed to perinatal exposure during birth; many were of an unknown exposure. Vaccinating all newborns can help prevent the acquisition of HBV after birth.
Final Thoughts About the Birth Dose of Hep B Vaccine:
Vaccines work best when given before exposure, so that the immune system is primed to resist infection. The childhood vaccine schedule, including the birth dose of hepatitis B vaccine, is timed to protect children when they’re most vulnerable. In some cases, a later vaccination makes sense if the individual is unlikely to encounter the pathogen for a period of time. Human papillomavirus (HPV) vaccination at age 11 is a good example because HPV is solely a sexually transmitted disease. Hepatitis B virus is not. If someone acquires HBV as a baby, it's nearly guaranteed that person's life will be cut short by liver disease.
