How does hepatitis B vaccination work?

The vaccine does not contain whole live hepatitis B virus, so it cannot give you hepatitis B. Instead, it shows the immune system a recognisable part of the virus. Antibodies and immune memory can then respond more quickly if the virus enters the body. Protection depends on completing the schedule advised for your age and circumstances.

Hepatitis B can spread through infected blood or body fluids, including during sexual contact or from a mother to her baby. Vaccination is preventive and does not clear an existing infection or replace testing after a possible exposure.

Review your vaccination history with a clinician, especially if you work around blood, have a household or sexual contact with hepatitis B, are pregnant, or have a condition affecting immunity. Keep appointments for follow-up doses and retain your vaccination record. After a recent exposure, seek medical advice urgently because testing and additional preventive treatment may be time-sensitive.

A sore arm, tiredness or a mild fever may follow the injection. These effects are usually short-lived; use the aftercare guidance given by your vaccination service and avoid delaying assessment of symptoms that are severe or unusual.

Get urgent help for breathing difficulty, facial or throat swelling, widespread hives, collapse or rapidly worsening symptoms after vaccination. Arrange medical review for persistent fever or a reaction that does not settle. After a possible hepatitis B exposure, do not wait for symptoms: hepatitis B infection may have no early symptoms, and prompt assessment can guide testing and prevention.

Ask which hepatitis B schedule applies to you, whether testing is needed, when protection is expected, and what happens if a dose is late. Discuss pregnancy, kidney disease, immune suppression, previous vaccine reactions and any recent exposure.