Acute and Chronic Hepatitis B

What is hepatitis B?

Hepatitis B is an infection caused by the hepatitis B virus (HBV), affecting the liver. Sometimes it is a short-lived infection from which the person recovers completely; in others the virus stays in the body and chronic hepatitis B develops.

One of the important characteristics of hepatitis B is that chronic infection in particular can progress for years without giving any symptoms.

Long-standing infection can lead in some patients to fibrosis in the liver, to cirrhosis and to liver cancer. But today these risks can be reduced considerably with regular follow-up and, where needed, antiviral drugs.

How common is hepatitis B worldwide?

Hepatitis B is still one of the most important chronic viral infections in the world.

According to current World Health Organization estimates, about 240 million people were living with chronic hepatitis B in 2024. Around 900,000 new infections occur each year.

Around 1.1 million people worldwide are estimated to have died in 2024 from hepatitis B-related cirrhosis and liver cancer.

High as these figures are, hepatitis B has an important advantage: it can largely be prevented with an effective vaccine.

How is hepatitis B transmitted?

HBV can be transmitted through contact with the blood and certain body fluids of an infected person.

The chief routes of transmission are:

• Transmission from an infected mother to her baby, particularly during birth,
• Unprotected sexual intercourse,
• Sharing needles or syringes,
• Non-sterile medical or surgical procedures,
• Non-sterile tattooing and piercing,
• Sharing personal items on which blood may be present, such as razors,
• Contact with infected blood, and accidents such as needlestick injuries in healthcare workers.

How is hepatitis B not transmitted?

Hepatitis B is not transmitted by:

• Embracing,
• Shaking hands,
• Being in the same room,
• Coughing or sneezing,
• Eating from the same plate,
• Food or water,
• Everyday social contact.

For this reason people carrying hepatitis B do not need to be kept away from their families or their social circle.

What is acute hepatitis B?

The first period after the virus enters the body is called acute hepatitis B.

Some people pass through this period with no symptoms at all. Where symptoms do develop, there may be:

• Weakness and tiredness,
• Loss of appetite,
• Nausea and vomiting,
• Abdominal pain,
• Muscle and joint pains,
• Darkening of the urine,
• Paling of the colour of the stool,
• Yellowing of the eyes and skin.

The great majority of people who catch hepatitis B as adults clear the virus on their own and recover completely.

In a very small number of patients the acute infection can run a severe course and lead to serious liver failure. The development of severe jaundice, a change in consciousness or a rapid deterioration in general condition requires emergency assessment.

Does acute hepatitis B become chronic?

Yes, but the risk of becoming chronic is closely related to the age at which the virus was acquired.

In healthy adults, the risk that a newly developed hepatitis B infection will become chronic is low. By contrast, where the virus is acquired during birth or in early childhood, the likelihood of it becoming chronic is far higher.

For this reason it is extremely important that the hepatitis B vaccine is given from birth.

What is chronic hepatitis B?

HBV infection continuing for longer than 6 months is generally regarded as chronic HBV infection.

Chronic hepatitis B may cause no complaints for years. The person may feel entirely healthy, and the infection may come to light only on blood tests.

But in some patients the virus can cause damage in the liver over time:

chronic HBV infection → inflammation in the liver → fibrosis → cirrhosis → the risk of liver cancer

This process does not develop in every patient with hepatitis B. The course of the disease can vary considerably from person to person.

How is hepatitis B diagnosed?

The diagnosis is made with blood tests. At first sight names such as HBsAg, anti-HBs and anti-HBc may look confusing. In fact each of them answers a different question.

HBsAg — the surface antigen of the virus. A positive HBsAg shows that current HBV infection may be present. How long it stays positive, and assessing it together with the other tests, matters in distinguishing acute from chronic infection.

Anti-HBs — the protective antibody formed against hepatitis B. A positive result generally shows that the person has gained immunity, either through vaccination or after an infection they have recovered from.

Anti-HBc — gives information about whether the person has met the actual hepatitis B virus. The hepatitis B vaccine on its own does not make anti-HBc positive.

IgM anti-HBc — important particularly in assessing a newly developed acute hepatitis B infection.

HBV DNA — shows the amount of virus in the blood. HBV DNA is one of the most important tests used in assessing chronic hepatitis B and in reaching a decision on treatment.

What do the hepatitis B tests mean, in brief?

HBsAg (−), anti-HBs (+), anti-HBc (−) → immunity may have developed through vaccination.

HBsAg (−), anti-HBs (+), anti-HBc (+) → hepatitis B may have been had before and recovered from.

HBsAg (+), IgM anti-HBc (+) → acute hepatitis B may be considered.

HBsAg (+) for longer than 6 months → chronic HBV infection is considered.

Because these results can have different meanings in certain particular situations, the hepatitis B tests have to be assessed together rather than one by one.

What investigations are done in chronic hepatitis B?

In a person found to be HBsAg positive, what is investigated is not only the presence of the virus but how active the virus is and whether the liver has been affected.

Depending on the patient, the following may be requested:

• ALT and AST,
• Bilirubin,
• Albumin,
• INR,
• A full blood count and platelets,
• HBeAg and anti-HBe,
• HBV DNA,
• Kidney function tests,
• Ultrasound of the liver,
• Elastography (FibroScan and the like),
• Blood tests that assess fibrosis.

Today, in many patients, blood tests and elastography can be used to assess fibrosis in the liver without a biopsy.

How is acute hepatitis B treated?

In the great majority of people who have acute hepatitis B, no specific antiviral treatment is needed.

The basis of treatment is observing the patient, ensuring adequate fluids and nutrition, and avoiding substances that could damage the liver.

But in patients whose acute hepatitis B runs a very severe course, or who develop acute liver failure, close observation in hospital and in some situations antiviral treatment may be needed.

Can chronic hepatitis B be treated?

Yes. But there is an important difference between the treatment of hepatitis B and the treatment of hepatitis C.

While hepatitis C today can result in the complete elimination of the virus in most patients, the main aim of the treatments available in chronic hepatitis B is mostly to suppress the multiplication of the virus strongly and to protect the liver.

The powerful antiviral drugs used often today include tenofovir and entecavir.

Treatment:

• Suppresses HBV DNA,
• Reduces the progression of damage in the liver,
• Reduces the risk of cirrhosis developing,
• May reduce the risk of liver cancer,
• Improves long-term life expectancy.

The length of treatment varies from patient to patient, and in some people it may need to continue for many years.

Does every HBsAg-positive patient need to take medicine?

No.

Not everyone found to be HBsAg positive has to start an antiviral drug straight away.

The chief factors that have to be assessed together in the treatment decision are:

• The HBV DNA level,
• The ALT level,
• Whether there is fibrosis or cirrhosis in the liver,
• The patient’s age,
• A family history of liver cancer or cirrhosis,
• Accompanying illnesses,
• The use of treatments that suppress the immune system,
• Other individual risk factors.

For this reason some patients receive treatment while others are followed regularly without medicine.

That medicine is not needed does not mean the disease does not need to be followed.

Is follow-up needed for liver cancer?

Chronic hepatitis B can increase the risk of hepatocellular carcinoma (liver cancer), particularly in certain risk groups.

The level of risk varies with the patient’s age and sex, the presence of cirrhosis, family history, HBV activity and other factors.

In patients at risk, regular screening with ultrasound of the liver at intervals set by the doctor may be needed.

How can hepatitis B be prevented?

Hepatitis B differs from HCV in one important way:

There is an effective vaccine against hepatitis B.

The most effective ways of protecting oneself are:

• Having the hepatitis B vaccine,
• Vaccinating babies from birth,
• Not sharing needles and syringes,
• Not sharing personal items that could come into contact with blood, such as razors,
• Having tattooing and piercing done in sterile conditions,
• Taking appropriate precautions where there is contact with blood,
• Protection against sexual transmission,
• Testing the partners and close contacts of HBsAg-positive people and vaccinating them if they are not immune.

Identifying HBsAg-positive pregnant women also matters. There are specific protective measures for mother and baby to prevent transmission to the baby during birth.

Hepatitis B and treatments that suppress the immune system

In people who have had hepatitis B in the past or who currently have HBV infection, the virus can reactivate during chemotherapy, certain biological drugs and other powerful immunosuppressive treatments.

For this reason it is important that hepatitis B tests are assessed before such treatments are started.

Where needed, serious HBV flares can be prevented by starting preventive antiviral treatment.

The important message

Hepatitis B can be prevented, followed up and, where needed, treated effectively.

While acute hepatitis B settles on its own in the great majority of adults, chronic hepatitis B can continue for years without symptoms.

A positive HBsAg does not on its own show how serious the disease is. HBV DNA, the liver tests and the degree of fibrosis in the liver must be assessed together.

In chronic hepatitis B the aim is not merely to correct the laboratory values but to prevent cirrhosis and liver cancer from developing and to keep the liver healthy for many years.

This content has been prepared for general information. Because the interpretation of hepatitis B tests, the frequency of follow-up and the decision on treatment can vary from person to person, they should be assessed by a doctor.