Key facts
- Hepatitis B is a viral infection that attacks the liver and can cause both acute and chronic diseases.
- The virus is most commonly transmitted from mother to child during birth and delivery, as well as through contact with blood or other body fluids during sex with an infected partner, unsafe injections, or exposure to sharp instruments.
- Hepatitis B can be prevented by vaccines that are safe, available, and effective.
Overview
Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus (HBV). It is a major global health problem. It can cause chronic infection and puts people at high risk of death from cirrhosis and liver cancer.
A safe and effective vaccine that offers 98% to 100% protection against hepatitis B is available. Preventing hepatitis B infection averts the development of complications including chronic disease and liver cancer.
The burden of hepatitis B infection is highest in the WHO Western Pacific Region and the WHO African Region, where 116 million and 81 million people, respectively, are chronically infected. Sixty million people are infected in the WHO Eastern Mediterranean Region, 18 million in the WHO South-East Asia Region, 14 million in the WHO European Region, and 5 million in the WHO Region of the Americas.
Transmission
In highly endemic areas, hepatitis B is most commonly spread from mother to child at birth (perinatal transmission) or through horizontal transmission (exposure to infected blood), especially from an infected child to an uninfected child during the first 5 years of life. The development of chronic infection is common in infants infected from their mothers or before the age of 5 years.
Hepatitis B is also spread by needlestick injury, tattooing, piercing, and exposure to infected blood and body fluids, such as saliva and menstrual, vaginal, and seminal fluids. Transmission of the virus may also occur through the reuse of contaminated needles and syringes or sharp objects either in health care settings, in the community, or among persons who inject drugs. Sexual transmission is more prevalent in unvaccinated persons with multiple sexual partners.
Hepatitis B is also spread by needlestick injury, tattooing, piercing, and exposure to infected blood and body fluids, such as saliva and menstrual, vaginal, and seminal fluids. Transmission of the virus may also occur through the reuse of contaminated needles and syringes or sharp objects either in health care settings, in the community, or among persons who inject drugs. Sexual transmission is more prevalent in unvaccinated persons with multiple sexual partners.
Hepatitis B infection acquired in adulthood leads to chronic hepatitis in less than 5% of cases, whereas infection in infancy and early childhood leads to chronic hepatitis in about 95% of cases. This is the basis for strengthening and prioritizing infant and childhood vaccination.
The hepatitis B virus can survive outside the body for at least 7 days. During this time, the virus can still cause infection if it enters the body of a person who is not protected by the vaccine. The incubation period of the hepatitis B virus ranges from 30 to 180 days. The virus may be detected within 30 to 60 days after infection and can persist and develop into chronic hepatitis B, especially when transmitted in infancy or childhood.
Symptoms
Most people do not experience any symptoms when newly infected. However, some people have acute illness with symptoms that last several weeks, including yellowing of the skin and eyes (jaundice), dark urine, extreme fatigue, nausea, vomiting, and abdominal pain. People with acute hepatitis can develop acute liver failure, which can lead to death. Among the long-term complications of HBV infections, a subset of persons develops advanced liver diseases such as cirrhosis and hepatocellular carcinoma, which cause high morbidity and mortality.
Diagnosis
It is not possible on clinical grounds to differentiate hepatitis B from hepatitis caused by other viral agents, hence laboratory confirmation of the diagnosis is essential. Several blood tests are available to diagnose and monitor people with hepatitis B. They can be used to distinguish acute and chronic infections. WHO recommends that all blood donations be tested for hepatitis B to ensure blood safety and avoid accidental transmission.
Treatment
There is no specific treatment for acute hepatitis B. Therefore, care is aimed at maintaining comfort and adequate nutritional balance, including the replacement of fluids lost from vomiting and diarrhea. Most important is the avoidance of unnecessary medications. Acetaminophen, paracetamol, and medication against vomiting should be avoided.
Chronic hepatitis B infection can be treated with medicines, including oral antiviral agents. Treatment can slow the progression of cirrhosis, reduce the incidence of liver cancer and improve long-term survival. In 2021 WHO estimated that 12% to 25% of people with chronic hepatitis B infection will require treatment, depending on setting and eligibility criteria.
WHO recommends the use of oral treatments (tenofovir or entecavir) as the most potent drugs to suppress the hepatitis B virus. Most people who start hepatitis B treatment must continue it for life.
In low-income settings, most people with liver cancer die within months of diagnosis. In high-income countries, patients present to hospitals earlier in the course of the disease and have access to surgery and chemotherapy which can prolong life for several months to a few years. Liver transplantation is sometimes used in people with cirrhosis or liver cancer in high-income countries, with varying success.
Prevention
WHO recommends that all infants receive the hepatitis B vaccine as soon as possible after birth, preferably within 24 hours, followed by 2 or 3 doses of hepatitis B vaccine at least 4 weeks apart to complete the vaccination series. Protection lasts at least 20 years and is probably lifelong. WHO does not recommend booster vaccinations for persons who have completed the 3-dose vaccination schedule.
In addition to infant vaccination, WHO recommends the use of antiviral prophylaxis for the prevention of hepatitis B transmission from mother to child. Implementation of blood safety strategies and safer sex practices, including minimizing the number of partners and using barrier protective measures (condoms), also protect against transmission.
