Immunity and viral serology . Patient guide
Hepatitis B immunity (anti-HBs) Blood Test
Also known as: Hepatitis B surface antibody, HBsAb, Hep B immunity
What is anti-HBs
The hepatitis B surface antibody (anti-HBs) measures whether your immune system has produced protective antibodies against the hepatitis B virus, either from past vaccination or from cleared past infection. A level of 10 mIU/mL or higher is generally considered protective in UK guidance.
This biomarker entry is being clinically reviewed by our team. The factual content draws on UK guidance (NICE, NHS, Royal Colleges and the relevant speciality society where cited).
Reference range
Reported in mIU/mL. Final reports always carry the issuing laboratory's range, which is what your clinician will interpret against.
| Group | Range | Note |
|---|---|---|
| No immunity | less than 10 mIU/mL | Vaccination or revaccination usually recommended |
| Protective immunity | 10 mIU/mL or higher | WHO and UK Green Book threshold for protection |
| Responder level | 100 mIU/mL or higher | UK Green Book Chapter 18 preferred level confirming an adequate vaccine response |
What it is
Anti-HBs is a specific antibody made against the surface protein of the hepatitis B virus. It is the marker used to confirm response to hepatitis B vaccination, to check immunity in healthcare and care workers, and to assess whether someone who has been exposed in the past has cleared the virus and is now immune. Anti-HBs is different from HBsAg, which detects current hepatitis B infection (the marker on our BBV panel).
Why a clinician would order it
Anti-HBs is requested after a course of hepatitis B vaccination to confirm seroconversion, before starting work or training in healthcare or care settings, before international travel to higher-prevalence areas, in pre-pregnancy planning, in chronic kidney disease or before immunosuppressive therapy, and in patients with a past history of hepatitis B to confirm clearance.
What your anti-HBs result means
Laboratory reports use different wording for the same result. Here is what each one means. This is general information, not a personal interpretation: a GMC-registered clinician should review your result against your history.
Anti-HBs 10 IU/L or higher (reactive / positive)
You have a protective level of hepatitis B surface antibody, normally from successful vaccination (or, less often, cleared past infection). 10 IU/L or higher is the accepted UK threshold for protection. A level of 100 IU/L or higher after a vaccine course indicates a strong responder; 10 to 99 IU/L may prompt a single booster in some occupational settings.
Anti-HBs below 10 IU/L (non-reactive / negative)
Your surface-antibody level is below the protective threshold, so you are not currently protected against hepatitis B. This is common before vaccination, after waning immunity, or in non-responders. A vaccine course or booster is usually offered, and the level rechecked 1 to 2 months after completion. Your clinician will also consider whether other hepatitis B markers (HBsAg, anti-HBc) are needed to rule out infection.
Anti-HBs reactive but HBsAg also positive
This combination is uncommon and needs clinical interpretation, because surface antibody and surface antigen are not usually positive together. It can occur in particular phases of infection or with certain virus variants. A clinician should review the full hepatitis B panel rather than reading anti-HBs alone.
If your level is outside the range
Symptoms of low anti-HBs
- No symptoms attributable to low anti-HBs; the relevance is in lacking protection against any future hepatitis B exposure.
What low can indicate. No previous vaccination, or non-response to the standard primary vaccination schedule (around 10 to 15 percent of adults do not reach a protective anti-HBs level after a first course, rising with age and in smokers, immunosuppression or chronic kidney disease per UK Green Book Chapter 18). A booster or repeat course is usually offered. Low immunity does not mean current infection, but does mean no current protection.
Symptoms of high anti-HBs
- A high anti-HBs is a positive finding indicating strong immunity, with no clinical symptoms attached.
What high can indicate. Successful response to hepatitis B vaccination or cleared natural infection with retained protective immunity. No further action is needed beyond standard re-checks where indicated by occupational health.
Testing tips
No fasting required. If checking response to vaccination, time the test at least 4 weeks after the final dose for the most reliable result. This test does not screen for current hepatitis B infection: that requires HBsAg, which is part of our BBV screen panel.
Sources
UK guidance our clinicians use when interpreting this marker.
This page is general patient information, not personal medical advice. A GMC-registered clinician will review your results and tailor any interpretation to you. See our Editorial Policy for how we write and review content.
Common questions about anti-HBs
What is a normal anti-HBs range?
No immunity: less than 10 mIU/mL (Vaccination or revaccination usually recommended). Protective immunity: 10 mIU/mL or higher (WHO and UK Green Book threshold for protection). Responder level: 100 mIU/mL or higher (UK Green Book Chapter 18 preferred level confirming an adequate vaccine response). Always interpret your own results against the laboratory range printed on your report, since assay-specific reference ranges vary.
What does a low anti-HBs result mean?
No previous vaccination, or non-response to the standard primary vaccination schedule (around 10 to 15 percent of adults do not reach a protective anti-HBs level after a first course, rising with age and in smokers, immunosuppression or chronic kidney disease per UK Green Book Chapter 18). A booster or repeat course is usually offered. Low immunity does not mean current infection, but does mean no current protection.
What does a high anti-HBs result mean?
Successful response to hepatitis B vaccination or cleared natural infection with retained protective immunity. No further action is needed beyond standard re-checks where indicated by occupational health.
Do I need to fast or prepare for the anti-HBs blood test?
No fasting required. If checking response to vaccination, time the test at least 4 weeks after the final dose for the most reliable result. This test does not screen for current hepatitis B infection: that requires HBsAg, which is part of our BBV screen panel.
What does "Anti-HBs 10 IU/L or higher (reactive / positive)" mean?
You have a protective level of hepatitis B surface antibody, normally from successful vaccination (or, less often, cleared past infection). 10 IU/L or higher is the accepted UK threshold for protection. A level of 100 IU/L or higher after a vaccine course indicates a strong responder; 10 to 99 IU/L may prompt a single booster in some occupational settings.
What does "Anti-HBs below 10 IU/L (non-reactive / negative)" mean?
Your surface-antibody level is below the protective threshold, so you are not currently protected against hepatitis B. This is common before vaccination, after waning immunity, or in non-responders. A vaccine course or booster is usually offered, and the level rechecked 1 to 2 months after completion. Your clinician will also consider whether other hepatitis B markers (HBsAg, anti-HBc) are needed to rule out infection.
What does "Anti-HBs reactive but HBsAg also positive" mean?
This combination is uncommon and needs clinical interpretation, because surface antibody and surface antigen are not usually positive together. It can occur in particular phases of infection or with certain virus variants. A clinician should review the full hepatitis B panel rather than reading anti-HBs alone.
Can I order a anti-HBs blood test privately in London?
Yes. WMG Health offers anti-HBs as part of bespoke panels and several pre-built panels at our 134 Harley Street clinic. Results are clinician-reviewed by a GMC-registered doctor within 4 hours for the most common assays. All panels are custom-built around your specific question; bookings via /contact/ or 020 3239 3378.