What is Hepatitis B?

Hepatitis B (HBV) is a viral infection that infects the liver and requires direct contact with infected blood or other body fluids to be transmitted.

Symptoms of hepatitis B usually appear after 90 days and last for a few weeks. Symptoms include fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, dark urine, discolored (clay) bowel movements, joint pain, and jaundice (yellowish skin or eyes).⁽¹⁾

About half of infected adults and children over the age of five have symptoms of the disease, while many children under the age of five do not.⁽²⁾

Most acute hepatitis B infections do not persist and become chronic, but if the infection lasts six months or longer and persists without being cleared, it can lead to chronic liver disease, liver cancer, and death.⁽³⁾

Hepatitis B infection is diagnosed through a blood test. People with an acute hepatitis B infection have a positive hepatitis B surface antigen (HBsAg). HBsAg can be detected in blood as early as one week after the onset of infection and can persist for up to nine weeks. People who clear the infection have a positive hepatitis B surface antibody (HBsAb) that can be detected in their blood. Blood tests can take six months or longer to indicate whether an acute infection has cleared up or has become chronic.⁽⁴⁾ People who recover from an acute hepatitis B infection and who clear the virus are immune for life.⁽⁵⁾

Is hepatitis B contagious?

Unlike other infectious diseases for which vaccines have been developed and mandated in the United States, hepatitis B is not common in childhood and is not highly contagious.⁽⁶⁾ Hepatitis B is primarily an adult disease that is most commonly transmitted through blood, but can also be transmitted through other body fluids such as semen and vaginal secretions.⁽⁷⁾ Hepatitis B is NOT spread through sneezing, kissing, sharing food or utensils, or breastfeeding.⁽⁸⁾ In many cases, transmission can be asymptomatic.⁽⁹⁾

Those most at risk of contracting hepatitis B are drug addicts who use needles; those who have had sexual contact with a person infected with hepatitis B; sexually promiscuous heterosexual and homosexual adults; residents and staff of custodial institutions such as prisons; healthcare workers exposed to blood; patients on hemodialysis and newborns born to infected mothers.⁽¹⁰⁾

The transmission of hepatitis B from an infected mother to a newborn has always been infrequent and continues to be so, especially thanks to routine prenatal screening of all pregnant women for hepatitis B infection. Newborns of mothers who tested positive for hepatitis hepatitis B or whose health status is unknown are treated with immunoprophylaxis with hepatitis B immunoglobulin (HBIG) to prevent transmission from mother to child.⁽¹¹⁾