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8 things people ask before getting the hepatitis B vaccination

1. What is hepatitis B?

Hepatitis B, or HBV, is one of several viruses that infect the liver. In many cases the infection is mild, you may not even notice symptoms, and the body fights the infection off. However, for some people, especially children and people with weakened immune systems, the chronic, long-term infection can occur. If left untreated, chronic hepatitis B infection can lead to serious liver problems, including cirrhosis and cancer.

2. How do you catch hepatitis B?

Hepatitis B is transmitted through direct contact with infected blood or bodily fluids. In developing countries, most people with hepatitis B acquire the virus at birth, from their mother, and infection develops in childhood. The UK is a very low prevalence country so your risk of catching HBV as an adult can often depend on your occupation, lifestyle or behaviours. One of the most common ways of catching HBV is accidental exposure at work, for example, if you are a healthcare worker, or work in a prison, care setting or mortuary. People who travel to countries where HBV infection is common are also at risk, especially if they require medical treatment whilst abroad. There is also a high risk of contracting HBV by having unprotected sex with an infected person or by sharing needles or drug equipment, or by having medical treatment or tattoos in unhygienic environments.

3. Who should be vaccinated against hepatitis B?

Since 2017 vaccination against HBV has been included in the childhood immunisation programme. Babies are vaccinated at 8 weeks, 12 weeks and 16 weeks of age with a vaccine that protects against six different diseases, including hepatitis B. Any adult or child that is at risk of exposure to HBV should protect themselves through vaccination. This includes people at occupational risk, people travelling to high-prevalence countries, people who inject drugs, sex workers and people attending sexual health clinics.

4. How many injections will I need?

Full protection against HBV requires multiple vaccine doses, the exact schedule will depend on your level of risk. Most people will need four doses of vaccine in total; three doses given one month apart followed by a fourth dose 12 months after the first. People at very high risk, or travelling abroad within one month may be offered an accelerated schedule with a dose given on day 0, day 7 and day 21. The fourth ‘booster’ dose is also required after 12 months to ensure ongoing protection.

5. How effective is HBV vaccination?

HBV vaccines are very effective for most people. Studies have shown a full course of vaccines gives over 95% protection against disease for more than 90% of people, especially children. It is known that some adults do not develop an effective antibody response after vaccination. The risk of a non-response is higher in men, people aged over 40, obesity, smokers and high alcohol consumption. A test is available to check that you have sufficient antibodies in your blood, and if not, a further course of vaccine is recommended.

6. How long will protection against hepatitis B last?

People who have received a full course of four doses of HBV vaccine can expect long-lasting protection infection. It is not known exactly how long protection lasts but it is at least 20 to 30 years. Further booster doses are not considered necessary unless you are a healthcare worker or you are directly exposed to HBV-infected blood or bodily fluids.

7. Are there any side effects to the vaccine?

The side effects of HBV vaccines are generally mild and short-lived for most people. The most common side effects include soreness, redness or swelling at the injection site, a high temperature, headache, upset stomach or generally feeling unwell. Some very rare effects have been reported in people who have received HBV vaccine, but they are so rare it cannot be confirmed if they are due to the vaccine or would have occurred anyway.

8. What if I decide not to get vaccinated?

People who have not been vaccinated against HBV and are exposed to contaminated blood or bodily fluids can be given HBV vaccine in what is known as post-exposure prophylaxis. The first dose is needed as soon as possible after exposure, ideally within 24 hours, but may still be effective up to 7 days after exposure. A special injection of hepatitis B antibodies is also given at the same time to provide protection whilst waiting for the vaccine to have its effect.  A full course of HBV vaccine is needed in order to prevent chronic infection from developing. If the first dose is given too late or the course is not completed, an infection may develop.


1. Public Health England (PHE); Hepatitis B: the green book, chapter 18; Published 20 March 2013, Last updated 18 December 2019;

2. NHS: Health A–Z: Hepatitis B: Last reviewed 30 January 2019;

3. Summary of medicinal Product Characteristics (SmPC), Engerix® B 20 micrograms/1 ml Suspension for injection in pre-filled syringe; GlaxoSmithKline UK Limited, updated 11-November-2020. Accessed online via The electronic Medicines Compendium;

4. Summary of medicinal Product Characteristics (SmPC), HBVAXPRO® 10 micrograms, suspension for injection; Merck Sharp & Dohme (UK) Limited, updated 10-Nov-2021. Accessed online via The electronic Medicines Compendium;

5. Summary of medicinal Product Characteristics (SmPC), Fendrix® suspension for injection; GlaxoSmithKline UK Limited, updated 21-April-2021. Accessed online via The electronic Medicines Compendium;

6. NHS: Health A–Z: Hepatitis B vaccine; Last reviewed 02 November 2021;