Understanding Hepatitis B Virus Infection

Hepatitis B is an infection of the liver caused by the hepatitis B virus, which most people who live with it long term picked up at birth or in early childhood without ever knowing [1,4].

This page provides general information. It does not replace advice from a doctor or another qualified healthcare professional.

Key facts

Hepatitis B is not spread by sharing food or drinks, hugging, kissing, coughing, sneezing or ordinary daily contact [3,13].
Whether an infection becomes long term depends mostly on how old a person was when it happened. Around 9 in 10 infected babies keep the virus for life, while around 95 percent of adults who catch it clear it completely [4].
The World Health Organization estimates that 240 million people were living with long-term hepatitis B in 2024 [1].
Most people do not know they have it. In 2024, only about 27 percent of people living with the infection were aware of it [1].
Long-term hepatitis B is usually silent for decades, so it is found by a blood test rather than by symptoms [3].
A safe vaccine prevents hepatitis B, and it works. The share of children under five living with the infection has fallen from around 5 percent before vaccination programs to 0.6 percent in 2024 [1].

What is hepatitis B?

Hepatitis means inflammation of the liver. Hepatitis B, also called hep B, is caused by the hepatitis B virus, or HBV, which reaches the liver through the bloodstream and multiplies inside liver cells [4,8,16]. The liver cleans the blood, stores energy and helps blood to clot [8].

Short-term and long-term infection

Acute hepatitis B clears within six months, and some people feel unwell for a few weeks while others notice nothing [3,7]. Chronic hepatitis B means the virus is still there after six months, and it is usually lifelong. Over years it can scar the liver, raising the chance of cirrhosis and liver cancer [1,3].

Age at the time of infection decides almost everything

Around 90 percent of babies infected at birth keep the virus for life, as do around 30 percent of children infected between one and five. Around 95 percent of infected adults clear it, with no lasting liver damage [4].

So the great majority of people living with long-term hepatitis B were infected as babies or small children, at an age when nobody had any say in it [1,16]. Nobody chooses to have this infection, and having it says nothing about how a person has lived.

How common is it?

The World Health Organization estimates that 240 million people were living with long-term hepatitis B in 2024, with around 0.9 million new infections a year and 1.1 million deaths, mostly from cirrhosis and liver cancer [1].

Most do not know: only around 27 percent were aware of their infection in 2024, and in the United States about 1 in 2 people with hepatitis B do not know [1,3].

It is spread unevenly, from 102 million people in the Western Pacific region and 64 million in Africa to 9.7 million in Europe and 5 million in the Americas [1]. Around 640,000 adults in the United States are affected [3], the chance of catching it within the United Kingdom is low [7], and in Australia around 70 percent of long-term infections are in people born overseas [19].

Other sources give around 300 million or nearly 259 million, using different years and methods [8,17]. All are estimates, since most people are undiagnosed.

What causes it?

Hepatitis B is an infection, not an inherited condition, and it is not carried in genes. It spreads when blood or certain body fluids from an infected person get into the body of someone who is not protected [3,4].

The main routes are:

From mother to baby during birth. Where the infection is common this is the usual route, through blood exchanged during delivery, not the genes [1,11,13].
Between young children. Contact where there are open cuts and sores, especially before the age of five [1].
Through blood. Unsterile medical, dental or tattooing equipment, shared injecting equipment, needlestick injuries, and transfusions where blood is not screened. Razors, toothbrushes and nail clippers can carry tiny amounts of blood [1,3,13].
Through sex without a condom or dam with a partner who has the virus [1,7].

How hepatitis B is not spread

Most of the social harm around hepatitis B comes from beliefs that are simply wrong. It is not spread by sharing food, drinks or eating utensils, by hugging, by kissing, by coughing or sneezing, by breastfeeding, or by ordinary contact at home, at school or at work [3,13]. The virus is found in saliva, and it is still not passed on by kissing or sharing cutlery [3].

The Hepatitis B Foundation answers the question people are most afraid to ask: yes, you can and should hug your loved ones [13].

What are the symptoms?

Most people notice nothing when newly infected [1]. Long-term infection is usually silent too, often for decades, and symptoms appear only once the liver has been damaged [3].

An acute illness usually lasts one to three months. It can bring yellowing of the skin and the whites of the eyes, harder to see on brown or black skin, dark urine, pale stools, tiredness, fever, joint pain, loss of appetite, nausea and abdominal pain [1,3,7]. Adults aged 30 and over are more likely to feel unwell than younger people [4].

When to seek urgent help. A severe acute infection can occasionally lead to liver failure, and most people with hepatitis B will never experience this [1]. Contact a doctor or emergency service straight away if yellowing of the skin or eyes appears, or there is vomiting of blood, black tarry stools, confusion, unusual drowsiness, swelling of the abdomen or legs, or vomiting that stops you keeping fluids down [1,7].

How is it diagnosed?

A blood test is the only way to know [5]. A family doctor can order it, and care is usually shared with a liver specialist, called a hepatologist [3,7].

The three-part panel. One sample of blood is enough, and three results are read together. This is the part people are handed without explanation [4,9]:

HBsAg, hepatitis B surface antigen. Positive means the virus is in the body now, and further tests show whether the infection is new or long term [9].
anti-HBs, or HBsAb, surface antibody. Positive means a person is protected, from the vaccine or from clearing a past infection [9].
anti-HBc, or HBcAb, core antibody. Positive means the body has met the virus at some point. Alone it cannot say whether that was past or present, which is why it only makes sense alongside the other two [9].

Tests that follow. A viral load test, written HBV DNA, measures how much virus is in the blood, and liver enzyme tests, ALT and AST, show whether liver cells are being injured [12]. An ultrasound pictures the liver, and elastography, or FibroScan, measures liver stiffness, which reflects scarring [1,12].

Who should be tested. The Centers for Disease Control and Prevention recommends testing every adult at least once, and every pregnant woman in each pregnancy [3,5]. WHO recommends offering it to all adults where more than 2 in 100 people are affected [1]. Diagnosis is often late because there was nothing to notice.

How is it treated?

Acute infection. There is no medicine for it. Care focuses on rest, food and fluids, with hospital treatment if the illness is severe [1,6]. Long-term infection cannot yet be cured. Treatment controls the virus rather than removing it, lowering the chance of cirrhosis and liver cancer [1,7,16].

Not everyone needs medicine, and that is a plan rather than neglect. A doctor decides by reading the viral load, liver enzyme results, scans and family history together [12]. Where those are reassuring, the right course is monitoring, so treatment can start when it will do most good. The check-ups are the part to hold on to [6,12].

The medicines. The main treatments are tablets taken once a day, usually tenofovir or entecavir, and most people who start them continue for life, with injected interferon-type medicines an alternative in some cases [1,10,12]. Either way the liver is checked every three to six months, with blood tests and scans, so problems including liver cancer are found early [6,10].

Pregnancy. Where the viral load is very high, or HBeAg is positive and viral load testing is unavailable, an antiviral medicine in the last three months of pregnancy lowers the chance of passing the virus on. The baby is given the first dose of hepatitis B vaccine as soon as possible after birth, which together with hepatitis B immune globulin, an injection of ready-made antibodies, protects more than 9 in 10 babies. Immune globulin is recommended in the United States, is not part of the WHO recommendation and is unavailable in some countries, so the birth dose of vaccine is the step to insist on [11].

Vaccination. The vaccine is safe and offers nearly complete protection. WHO advises a dose for every baby within 24 hours of birth, then two or three more at least four weeks apart, protecting for at least 20 years and probably for life [1]. Among children under five, the share living with hepatitis B has fallen from around 5 percent before vaccination to 0.6 percent in 2024 [1]. Access to treatment is far less equal: in 2024 only about 4.3 percent of people with long-term hepatitis B were receiving antiviral medicine, while WHO’s guidelines suggest more than half would benefit [1].

Living with hepatitis B

Check-ups continue even when nothing feels wrong [6,10]. It helps to limit alcohol, to be vaccinated against hepatitis A, to be tested for hepatitis C, hepatitis D and HIV, and to ask a doctor before taking any supplement or herbal remedy, since some harm the liver [3,6]. Household members and partners can be protected by vaccination [1,7].

The hardest part is often social rather than medical. Stigma and discrimination are well documented, and people have been kept out of school places and jobs because of their status [17]. In interviews with people living with the infection in the United States, China and Poland, every participant described stigma they had turned inward on themselves [18]. None of it is a reflection on the person carrying it. Liver charities run free nurse-led helplines, and patient-led organizations exist for this reason.

Thinking about a clinical trial?

Clinical trials test whether a treatment works and is safe. Deciding whether to look into one is personal, and it helps to take it in steps.

1. Understand what the study is asking

What a study involves:

what the researchers want to learn, and whether the goal is controlling the virus, clearing the surface antigen or improving testing
what is being studied, and what it is compared with, often a current antiviral tablet
how long it lasts, and whether there is follow-up after treatment ends
what visits and tests are involved, how far you would travel, and how often
the possible benefits, the known and unknown risks, and what happens at the end
whether your usual antiviral tablet continues, pauses or changes, and who monitors you

Studies here often run a year or longer, since the liver changes slowly.

2. Consider possible medical suitability

Every trial has rules about who can take part, called eligibility criteria. For a hepatitis B study they might include a confirmed long-term infection, a surface antigen or viral load reading inside a stated range, liver enzyme results within set limits, time already on a current antiviral tablet, a stated stage of liver scarring, and no other infection such as hepatitis C, hepatitis D or HIV. Some ask about pregnancy plans.

trialport’s medifit helps people consider information related to possible medical suitability. It does not diagnose a condition, confirm eligibility or replace formal screening by the study team.

Explore hepatitis B clinical trials through trialport

3. Consider whether participation fits your life

A study can look right on paper and still be hard in practice:

the time each visit takes, and how many there are in total
how blood tests and scans would fit around work, school or caring for others
travel, distance and who would come with you
whether taking part would mean telling anyone about your hepatitis B status
whether a study asks you to stop or change a medicine you rely on, and whether that is realistic
who supports you, and whether you understand the study well enough to decide

trialport’s readifit helps people reflect on their understanding, motivation, time, routines, support, emotions and practical arrangements.

4. Ask questions before deciding

Useful questions to put to a research team:

Why is this study being carried out, and what is already known?
What would I need to do, and for how long?
What are the known risks and side effects, and what is still unknown?
Could I receive a placebo? A placebo is a dummy treatment with no active medicine, used so researchers can compare results fairly. Would I still receive usual care alongside it?
Would I have to stop my current antiviral tablet, and what if the virus became active again?
How often would my liver be checked, and would I be told my results?
Who at the study site would know my hepatitis B status, and how is my information kept private?
Can I leave after joining, and what happens to my care if I do?

Taking part is voluntary. A person can ask questions, speak with people they trust and choose not to participate.

Search for clinical trials at app.trialport.com.

Current research

Working toward a functional cure. Researchers use this phrase for a treatment that clears the surface antigen from the blood and keeps the virus suppressed after treatment stops. It would not remove the stable viral DNA hiding inside liver cells, so it is not a complete cure. It would mean treatment lasting a set period rather than a lifetime [14].
A medicine under review. The Hepatitis B Foundation reported in April 2026 that the United States Food and Drug Administration is reviewing bepirovirsen with priority status and Breakthrough Therapy designation, with a decision expected by 26 October 2026. It is not approved anywhere, and a review is not an approval [15].
Treating more of the people who would benefit. WHO’s 2024 guidelines widened and simplified the rules on who should be offered treatment, extended them to adolescents, expanded antiviral medicine in pregnancy and encouraged viral load testing at the point of care [2].

Study status checked: 3 August 2026. Research moves quickly and what is being studied changes, so this list will date. For current information, search at app.trialport.com.

Support and further information

The Hepatitis B Foundation is the clearest starting point globally, with plain-language pages in many languages and a large question-and-answer library [8,13]. In the United States, the CDC hepatitis B pages cover testing, treatment and vaccination and correct the myths [3]. In the United Kingdom, NHS guidance explains what to expect and Liver UK adds personal stories and a free nurse-led helpline [7,16]. The World Hepatitis Alliance is led by people living with viral hepatitis and can point to members in many countries [20], and WHO’s fact sheet carries the global figures [1]. Coverage is thinner in several regions with the highest numbers of affected people.

Questions people often ask

Can I pass hepatitis B on by sharing food or hugging someone?
No. It is not spread by food, drinks, utensils, hugging, kissing, coughing, sneezing or everyday contact. The virus is found in saliva and still not passed on that way [3,13].

Did I do something to get this?
Almost certainly not. Most people with long-term hepatitis B were infected at birth or in early childhood, with no say in it at all [1,4].

Is there a cure?
Not yet. Treatment controls the virus and lowers the chance of serious liver disease, and most people who start it stay on it [1,7]. Research into a functional cure, meaning lasting control after treatment stops, is active [14].

Does everyone with hepatitis B need medicine?
No. Many people are monitored rather than treated, and a doctor decides using the viral load, liver enzyme results, scans and family history [6,12]. Monitoring is a real plan, and keeping the appointments is what makes it work.

Will I get cirrhosis or liver cancer?
Most do not [16]. Around 15 to 25 percent develop chronic liver disease, which is why regular checks are offered [4].

Can I have children?
Yes. Testing in pregnancy, antiviral medicine in the last three months where needed, and vaccination at birth protect more than 9 in 10 babies [11].

Do I have to tell people?
Who you tell is your decision, beyond healthcare staff who need to know to care for you safely. Stigma is well documented, including exclusion from education and work, so the caution many people feel is reasonable rather than irrational [17,18].

Sources

World Health Organization. Hepatitis B. Fact sheet, updated 28 July 2026. https://www.who.int/news-room/fact-sheets/detail/hepatitis-b Accessed 3 August 2026.
World Health Organization. Guidelines for the prevention, diagnosis, care and treatment for people with chronic hepatitis B infection. 2024. ISBN 978-92-4-009090-3. Overview and scope read on the publication page. https://www.who.int/publications/i/item/9789240090903 Accessed 3 August 2026.
Centers for Disease Control and Prevention. Hepatitis B Basics. Last reviewed 29 August 2025. https://www.cdc.gov/hepatitis-b/about/index.html Accessed 3 August 2026.
Centers for Disease Control and Prevention. Clinical Overview of Hepatitis B. Last reviewed 29 August 2025. https://www.cdc.gov/hepatitis-b/hcp/clinical-overview/index.html Accessed 3 August 2026.
Centers for Disease Control and Prevention. Testing for Hepatitis B. Last reviewed 31 January 2025. https://www.cdc.gov/hepatitis-b/testing/index.html Accessed 3 August 2026.
Centers for Disease Control and Prevention. Treatment of Hepatitis B. Last reviewed 12 January 2024. https://www.cdc.gov/hepatitis-b/treatment/index.html Accessed 3 August 2026.
National Health Service (United Kingdom). Hepatitis B. Page last reviewed 17 November 2025. https://www.nhs.uk/conditions/hepatitis-b/ Accessed 3 August 2026.
Hepatitis B Foundation. What Is Hepatitis B? https://www.hepb.org/what-is-hepatitis-b/what-is-hepb/ Accessed 3 August 2026.
Hepatitis B Foundation. Blood Tests for Diagnosing Hepatitis B. https://www.hepb.org/prevention-and-diagnosis/diagnosis/hbv-blood-tests/ Accessed 3 August 2026.
Hepatitis B Foundation. Treatment and Management: Treatment. https://www.hepb.org/treatment-and-management/treatment/ Accessed 3 August 2026.
Hepatitis B Foundation. Pregnancy and Hepatitis B. Page updated September 2020. https://www.hepb.org/treatment-and-management/pregnancy-and-hbv/ Accessed 3 August 2026.
Hepatitis B Foundation. Does everyone with chronic hepatitis B need to take medicine? Page updated 9 February 2022. https://www.hepb.org/what-is-hepatitis-b/faqs/does-everyone-with-chronic-hepatitis-b-need-to-take-medicine/ Accessed 3 August 2026.
Hepatitis B Foundation. If I have chronic hepatitis B infection, can I hug my children, partner or friend? Page updated 27 December 2022. https://www.hepb.org/what-is-hepatitis-b/faqs/if-i-have-chronic-hepatitis-b-infection-can-i-hug-my-children-partner-or-friend/ Accessed 3 August 2026.
Hepatitis B Foundation. I keep hearing about a “Functional Cure” for chronic hepatitis B, what does this mean? Page updated 27 December 2022. https://www.hepb.org/what-is-hepatitis-b/faqs/i-keep-hearing-about-a-functional-cure-for-chronic-hepatitis-b-what-does-this-mean/ Accessed 3 August 2026.
Hepatitis B Foundation. FDA reviewing new GSK treatment with priority status. News item, 28 April 2026. https://www.hepb.org/news-and-events/news-2/fda-reviewing-new-gsk-treatment-with-priority-status/ Accessed 3 August 2026.
Liver UK. Hepatitis B in adults. Content last reviewed July 2023, page updated 26 June 2026. https://liveruk.org/about-liver-disease/conditions/hepatitis-b/ Accessed 3 August 2026.
Ibrahim Y, Qureshi A, Jackson M, Zovich B, Freeland C, Flomo M, Alik K, Yakubov R, Chen LH, Yeboah PK, Cohen C. Why does hepatitis B remain underprioritized? A view through lived experience. World Journal of Methodology. 2026;16(2):114604. doi:10.5662/wjm.v16.i2.114604. Full text read via Europe PMC: https://europepmc.org/article/MED/42058812 Accessed 3 August 2026.
Smith V, Asriah M, Fernelius K, Das J, Grant L, Gielen V, Keith S. The Silent Burden of Hepatitis B-Related Stigma. Journal of Viral Hepatitis. 2026;33(8):e70212. doi:10.1111/jvh.70212. Abstract read via the Europe PMC public interface: https://europepmc.org/article/MED/42499137 Accessed 3 August 2026.
Baek Y, Horwitz R, Brener L, Okeke S, Broady T, Treloar C, Cama E. Understanding Hepatitis B Knowledge, Attitudes, and Stigma in the Korean Community in Australia. Journal of Racial and Ethnic Health Disparities. 2025. doi:10.1007/s40615-025-02622-3. Abstract read via the Europe PMC public interface: https://europepmc.org/article/MED/40965828 Accessed 3 August 2026.
World Hepatitis Alliance. Organization homepage and programs. https://www.worldhepatitisalliance.org/ Accessed 3 August 2026.

Review information

Written by: trialport editorial team
Reviewed by: Keith Berelowitz, Founder and CEO, trialport
Reviewed on: 3 August 2026
Next review due: 3 August 2027
References last checked: 3 August 2026

Hepatitis B: a plain-language guide