Engerix-B

What Is Engerix-B and What Is It Used For?

Engerix-B is a hepatitis B vaccine used to protect newborns, children and adolescents (up to 15 years) against infection by the hepatitis B virus. It contains a purified, non-infectious protein from the outer shell of the virus and stimulates the body to produce its own protective antibodies without causing the disease.

Hepatitis B is a serious infectious disease of the liver caused by the hepatitis B virus (HBV). The World Health Organization (WHO) estimates that approximately 254 million people worldwide are living with chronic hepatitis B infection, with over 1.1 million deaths each year from hepatitis B-related liver disease, including cirrhosis and hepatocellular carcinoma (liver cancer). Vaccination remains the single most effective strategy for preventing hepatitis B and its long-term complications.

Engerix-B contains small quantities of the hepatitis B virus surface antigen (HBsAg), which is the protein that forms the outer coat of the virus. This antigen is produced using recombinant DNA technology in yeast cells (Saccharomyces cerevisiae), meaning no actual virus is used in production. The HBsAg is then purified and adsorbed onto aluminium hydroxide, which acts as an adjuvant to enhance the immune response. Because the vaccine contains only a single viral protein and no genetic material from the virus, it is non-infectious and cannot cause hepatitis B.

When Engerix-B is administered, the immune system recognises the HBsAg as foreign and mounts an immune response. This results in the production of antibodies (anti-HBs) that specifically target the hepatitis B surface antigen. These antibodies remain in the body and provide protection against future exposure to the hepatitis B virus. If the vaccinated individual subsequently encounters the actual virus, the immune system can rapidly neutralise it before infection becomes established.

The hepatitis B virus is transmitted through contact with infected blood or body fluids. Common routes of transmission include mother-to-child transmission during birth (vertical transmission), unprotected sexual contact, sharing of needles or other injection equipment, and exposure to inadequately sterilised medical or dental instruments. Importantly, a mother who carries the virus can transmit it to her newborn during delivery, and infants infected at birth face up to a 90% risk of developing chronic hepatitis B. This is why neonatal vaccination is a critical public health measure.

Who Should Receive Engerix-B?

Engerix-B (10 mcg/0.5 mL formulation) is indicated for active immunisation against hepatitis B in newborns, infants, children and adolescents up to and including 15 years of age. The WHO recommends that all infants receive their first dose of hepatitis B vaccine within 24 hours of birth, followed by two or three additional doses to complete the primary series. In most countries, hepatitis B vaccination is included in the routine childhood immunisation schedule.

Vaccination is particularly important for individuals at higher risk of hepatitis B exposure, including infants born to mothers who are hepatitis B carriers, children in areas of high endemicity, children who require frequent blood products or haemodialysis, household contacts and sexual partners of persons with chronic hepatitis B, and healthcare workers or others who may be exposed to blood or body fluids occupationally.

Important Limitations

It is essential to understand that Engerix-B does not provide treatment for individuals who are already infected with hepatitis B. The vaccine provides only preventive (prophylactic) protection. If you have already been exposed to or infected with the hepatitis B virus, the vaccine will not clear the existing infection. Additionally, Engerix-B protects only against hepatitis B (and by extension, hepatitis D); it does not protect against hepatitis A, C, or E, which are caused by different viruses.

What Should You Know Before Receiving Engerix-B?

Before vaccination with Engerix-B, inform your healthcare provider about any allergies, current illnesses (especially fever), immune system disorders, or medications you are taking. The vaccine should not be given to anyone with a known allergy to any of its components or who has had a severe reaction to a previous dose.

Contraindications

Engerix-B should not be given if any of the following apply:

• Known allergy (hypersensitivity) to the active substance, to any of the excipients, or to any residual traces from the manufacturing process (such as yeast proteins) – symptoms may include rash, itching, swelling, or difficulty breathing
• Previous severe allergic reaction to a prior dose of Engerix-B or any other hepatitis B vaccine
• Acute febrile illness (high fever) – vaccination should be postponed until the fever has resolved. A minor illness without fever, such as a mild cold, is generally not a reason to delay vaccination

If you are unsure whether any of the above applies, speak to your doctor or healthcare provider before vaccination. Always inform the vaccinator about any allergies or previous adverse reactions following vaccination.

Warnings and Precautions

Talk to your doctor or healthcare provider before receiving Engerix-B if you or your child:

• Are on haemodialysis due to kidney problems – people undergoing haemodialysis may have a reduced immune response to the vaccine and may require additional doses or monitoring of antibody levels
• Have a condition affecting the immune system – including HIV infection, immunosuppressive therapy, or congenital immunodeficiency. These individuals may still receive the vaccine, but the immune response may be suboptimal and additional doses may be needed
• Have chronic liver disease or are a hepatitis C carrier – hepatitis B vaccination is particularly important in these individuals because a hepatitis B superinfection could significantly worsen their liver disease
• Have a bleeding disorder or are taking anticoagulant medication – the vaccine may be given subcutaneously instead of intramuscularly to reduce the risk of bleeding at the injection site

Fainting (syncope) can occur following, or even before, any needle injection. This is most common in adolescents. Tell your healthcare provider if you or your child has fainted during a previous injection so that appropriate precautions can be taken.

As with all vaccines, Engerix-B may not provide complete protection in every individual. Several factors can reduce the immune response to the vaccine, including older age, male sex, obesity, smoking, and chronic medical conditions. If any of these apply, your doctor may recommend checking antibody levels after vaccination and giving additional doses if needed to ensure adequate protection.

Other Medicines and Engerix-B

Tell your doctor or healthcare provider about all medicines being taken, or recently taken, including non-prescription medicines and herbal products. Engerix-B can be administered at the same time as most other routine childhood vaccines. When given simultaneously with other injectable vaccines, they must be administered using separate syringes and at different injection sites.

Immunosuppressive medications (such as corticosteroids, chemotherapy agents, or biological therapies) may reduce the immune response to Engerix-B. If you or your child is receiving immunosuppressive treatment, your doctor may recommend additional vaccine doses or post-vaccination antibody testing to confirm adequate protection.

Pregnancy and Breastfeeding

The effect of Engerix-B on foetal development has not been assessed in formal clinical studies. However, as with all inactivated vaccines, the risk to the foetus is considered minimal. As a precaution, vaccination during pregnancy should be avoided unless the potential benefits clearly outweigh the potential risks – for example, if the pregnant woman is at high risk of hepatitis B exposure. Always consult your doctor before receiving any vaccine during pregnancy or while breastfeeding.

Driving and Operating Machinery

Engerix-B is unlikely to affect your ability to drive or use machines. However, if you feel unwell after vaccination – for example, experiencing dizziness, headache, or fatigue – you should refrain from driving or operating machinery until the symptoms have resolved. You are responsible for assessing your own fitness to drive after vaccination.

Sodium Content

This vaccine contains less than 1 mmol sodium (23 mg) per dose, meaning it is essentially sodium-free. This is relevant for individuals on a sodium-restricted diet.

What Is the Correct Dosage of Engerix-B?

Engerix-B is administered as an intramuscular injection. Newborns, children and adolescents up to 15 years receive a 10 mcg/0.5 mL dose. The standard schedule is 3 doses at 0, 1 and 6 months, with an accelerated 4-dose schedule available for faster protection.

How the Vaccine Is Given

Engerix-B is given by injection and must be administered by a trained healthcare professional. The injection site depends on the age of the recipient:

• Children and adolescents: Injection into the upper arm muscle (deltoid muscle)
• Infants and young children: Injection into the upper outer thigh muscle (anterolateral thigh)
• Individuals with bleeding disorders: Subcutaneous injection may be used instead of intramuscular to reduce the risk of haematoma formation

The vaccine should never be injected into the buttock (gluteal muscle), as absorption from this site is unreliable and may result in a lower immune response. It should also never be given intravenously.

Standard Vaccination Schedule (Schema 1)

Accelerated Vaccination Schedule (Schema 2)

The accelerated schedule is particularly useful when rapid protection is needed, for example following known or suspected exposure to hepatitis B, or for infants born to hepatitis B-positive mothers. It can also be used when it is uncertain whether the individual will return for follow-up appointments at 6 months. With this schedule, Engerix-B can be given at the same time as other routine childhood vaccines.

Newborns Born to Hepatitis B-Positive Mothers

Infants born to mothers who are hepatitis B carriers (HBsAg-positive) require immediate vaccination. Either the standard 3-dose or the accelerated 4-dose schedule may be used. In addition, the doctor may administer hepatitis B immunoglobulin (HBIG) – concentrated human antibodies against HBV – at the same time as the first vaccine dose, but at a different injection site. The combination of active vaccination and passive immunisation with HBIG provides the highest level of immediate and long-term protection for the newborn, reducing the risk of vertical transmission to below 5%.

Individuals on Haemodialysis

Patients with kidney failure who are on haemodialysis often have an impaired immune response to hepatitis B vaccination. Your doctor may decide to check antibody levels (anti-HBs) after completing the vaccination series and may give additional booster doses if the antibody response is below the protective threshold of 10 mIU/mL. Periodic monitoring of anti-HBs levels is recommended for these individuals, with booster doses when antibody levels fall below the protective level.

Missed Dose

It is very important to complete the full vaccination series for optimal protection. If you or your child misses a scheduled dose, contact your healthcare provider as soon as possible. In general, missed doses do not require restarting the entire series – the vaccination can be continued from where it was interrupted. However, the interval between doses should not be shorter than the minimum recommended interval.

What Are the Side Effects of Engerix-B?

Like all vaccines, Engerix-B can cause side effects, but not everybody gets them. The most common side effects are injection-site reactions (pain, redness), headache, tiredness and irritability. Serious allergic reactions are very rare. Most side effects are mild and resolve on their own within a few days.

Allergic Reactions (Very Rare)

Side Effects by Frequency

Post-Marketing Reports

The following side effects have been reported very rarely after widespread use of Engerix-B since its market launch. Because these are reported voluntarily from an uncertain population size, it is not always possible to reliably estimate their frequency:

• Blood and immune system: Easy bruising, difficulty stopping bleeding (thrombocytopenia), low blood pressure, inflammation of blood vessels (vasculitis)
• Skin and allergic: Sudden swelling of face, throat and mouth area (angioneurotic oedema), dark purple or red-violet skin bumps (lichen planus)
• Nervous system: Paralysis (including Guillain-Barré syndrome, causing progressive weakness and numbness that may affect arms, legs, chest and face), optic neuritis (inflammation of the optic nerve), multiple sclerosis, encephalitis (brain inflammation), encephalopathy (degenerative brain disease), meningitis, seizures, neuropathy (nerve damage affecting movement of limbs), reduced sensitivity to pain or touch (hypoaesthesia)
• Musculoskeletal: Arthritis (joint pain and stiffness), muscle weakness

In very premature infants (born at or before 28 weeks of gestation), longer than normal gaps between breaths (apnoea) may occur for 2–3 days after vaccination. This is a known phenomenon and healthcare providers monitor premature infants appropriately following immunisation.

How Should Engerix-B Be Stored?

Engerix-B must be stored in a refrigerator at 2°C to 8°C (36°F to 46°F). It must not be frozen, as freezing destroys the vaccine and renders it ineffective. Keep the vaccine in its original packaging to protect it from light.

Proper storage of Engerix-B is critical to maintaining its effectiveness and safety. The following storage guidelines should be strictly observed:

• Temperature: Store in a refrigerator at 2°C to 8°C (36°F to 46°F) at all times
• Do not freeze: Freezing irreversibly damages the aluminium hydroxide adjuvant and the antigen structure, rendering the vaccine ineffective. If the vaccine has been frozen, it must be discarded
• Light protection: Keep in the original packaging to protect from light
• Expiry date: Do not use after the expiry date printed on the label and carton (EXP). The expiry date refers to the last day of the stated month
• Keep out of reach of children: Store the vaccine in a secure location inaccessible to children

Upon storage, a white sediment and a clear, colourless supernatant may be observed. This is normal and does not indicate deterioration. Before administration, the vaccine should be shaken well to obtain a slightly opaque, white suspension. If foreign particles are observed or the physical appearance is abnormal, the vaccine should not be administered.

Do not dispose of unused vaccines in household waste or via the sewage system. Ask your pharmacist or healthcare provider about proper disposal procedures. These measures help protect the environment.

What Does Engerix-B Contain?

The active substance in Engerix-B is the hepatitis B virus surface antigen (HBsAg), produced by recombinant DNA technology. Each 0.5 mL dose contains 10 micrograms of HBsAg adsorbed onto aluminium hydroxide as adjuvant. The vaccine also contains sodium chloride, disodium phosphate dihydrate, sodium dihydrogen phosphate, and water for injections.

Active Ingredient

Each 0.5 mL dose of Engerix-B contains 10 micrograms of hepatitis B virus surface antigen (HBsAg). This protein is manufactured using recombinant DNA technology, in which the gene encoding HBsAg is inserted into yeast cells (Saccharomyces cerevisiae). The yeast cells then produce the HBsAg protein, which is subsequently harvested and purified. The purified antigen is adsorbed onto hydrated aluminium hydroxide (0.25 mg Al³⁺), which serves as an adjuvant to enhance the immune response.

Other Ingredients (Excipients)

• Sodium chloride – helps create a solution that is compatible with the body's tissues (isotonic)
• Disodium phosphate dihydrate – a buffering agent that maintains the correct pH
• Sodium dihydrogen phosphate – a buffering agent that maintains the correct pH
• Water for injections – the solvent in which all ingredients are dissolved

Appearance and Pack Sizes

Engerix-B is a cloudy, white suspension for injection. It is supplied in pre-filled syringes containing a single dose, with or without separate needles, in pack sizes of 1 and 10. Not all pack sizes may be marketed in all countries.

The vaccine is manufactured by GlaxoSmithKline Biologicals s.a., Rue de l'Institut 89, B-1330 Rixensart, Belgium. It is authorised under various names across the European Economic Area (EEA), including Engerix-B in multiple countries, Engerix B Junior, and Engerix-B-10.

How Does Engerix-B Work?

Engerix-B works by training the immune system to recognise and defend against the hepatitis B virus. The vaccine contains a harmless viral protein (HBsAg) that stimulates the production of protective antibodies, providing long-lasting immunity without causing the disease.

The mechanism of action of Engerix-B is based on the principle of active immunisation. When the vaccine is injected, the recombinant hepatitis B surface antigen (HBsAg) is presented to the immune system. The body's antigen-presenting cells (such as dendritic cells and macrophages) recognise the HBsAg as a foreign protein and process it for presentation to T-helper lymphocytes.

This initiates a cascade of immune responses: T-helper cells activate B-lymphocytes, which then proliferate and differentiate into plasma cells that produce antibodies specifically directed against HBsAg (known as anti-HBs antibodies). Some B-cells also become long-lived memory B-cells, which persist in the body for years or decades and can rapidly produce anti-HBs antibodies upon future exposure to the hepatitis B virus.

The aluminium hydroxide adjuvant in the vaccine plays an important supporting role. It creates a depot effect at the injection site, slowly releasing the antigen over time. This prolonged antigen exposure enhances the activation of immune cells and results in a stronger and more durable antibody response compared to the antigen alone.

After completing the full vaccination series, protective antibody levels (anti-HBs ≥ 10 mIU/mL) are achieved in over 95% of healthy infants, children and adolescents. Studies with long-term follow-up have demonstrated that immunity persists for at least 20–30 years in immunocompetent individuals, and likely lifelong, owing to the persistence of immune memory cells. Even if antibody levels decline below the protective threshold over time, the immune memory (anamnestic response) typically allows for a rapid protective response upon exposure to the virus.

Frequently Asked Questions About Engerix-B