Infections
Hepatitis Bs al. (anti-HBs-titer)
Antibodies against hepatitis B as a number; shows whether you are protected after vaccination or a healed infection.
Everything about this testWhat it measures
Anti-HBs are IgG antibodies against the surface protein (HBsAg) of the hepatitis B virus. The body makes them after a hepatitis B vaccination or after a healed hepatitis B infection; they can also be present temporarily after hepatitis B immunoglobulin has been given. The result is a number, the titer, in international units per liter (IU/l). Anti-HBs alone cannot show whether the antibodies come from vaccination or from an infection; anti-HBc is needed for that.
- Protection (immunity) against hepatitis B after vaccination or a healed infection
- Insufficient response to vaccination (non-response): titer below 10 IU/l, measured 4 to 8 weeks after the last vaccination
High
A titer of 10 IU/l or higher, measured 4 to 8 weeks after a complete vaccination series, is considered protective according to the LCI guideline (RIVM). With a normal immune system, you can then assume lifelong protection and a new vaccination is not needed. For healthcare workers who perform procedures with a chance of blood contact with a patient, a stricter limit of 100 IU/l applies. After a healed hepatitis B infection, anti-HBs can also be detected and you are immune as well. Please note: in about 1 in 10 people with an active hepatitis B infection, anti-HBs can still be detected, usually between 10 and 99 IU/l; a protective titer therefore does not completely rule out an existing infection.
Low
A titer below 10 IU/l, measured 4 to 8 weeks after the last vaccination, means that the vaccination has not worked well enough (non-response). This is more common in people over 40, men, smokers, people with severe overweight and people with a weakened immune system. If the titer is measured years after the vaccination, a low or unmeasurable value is normal: in 7 to 50 out of 100 adults, the titer drops below 10 IU/l within 5 years. According to the LCI, protection after a successful vaccination then remains, because the immune memory quickly makes antibodies again on new contact with the virus. If you have never been vaccinated and never had hepatitis B, anti-HBs is negative and you are not protected.
If your result is abnormal
With a titer below 10 IU/l 4 to 8 weeks after vaccination, a new vaccination series usually follows according to the schedule for non-responders, sometimes together with a test for a past or active infection (HBsAg and anti-HBc). With a low titer years after a vaccination for which a titer was never measured, the doctor weighs up per situation between no action, a booster vaccination or a new measurement. Anti-HBs is a measurement of protection and is not notifiable.
Reliability
The limit of 10 IU/l is the agreed value for a protective titer in the Netherlands. The result can only be interpreted properly if it is known when you were vaccinated: the LCI guideline (RIVM) bases the assessment on a measurement 4 to 8 weeks after the last vaccination. In healthy adults under 40, more than 90 out of 100 have a protective titer after a complete vaccination; a check is mainly meaningful with an occupational risk, after vaccination because of a needlestick or sexual exposure incident, or with a weakened immune system. Anti-HBs says nothing about an active infection; HBsAg is needed for that.
Limitations
- The timing determines the meaning: years after vaccination, a low titer is normal and not proof of insufficient protection.
- After hepatitis B immunoglobulin has been given (for example after a needlestick injury), anti-HBs can be temporarily detectable without your own immune response.
- With an impaired immune system, the level and duration of protection are less certain, even with a titer above 10 IU/l.
- Results from different laboratories and measuring methods are not always exactly comparable.
How common is this
Since August 2011, all babies in the Netherlands have received the hepatitis B vaccination through the National Immunization Program; men who have sex with men and sex workers can be vaccinated free of charge at the GGD (municipal public health service). In healthy adults under 40, more than 90 out of 100 have a protective titer after three vaccinations, and about 75 out of 100 at age 60. Of adults, 7 to 50 out of 100 again have a titer below 10 IU/l within 5 years after vaccination.
Who is this useful for
Useful for people who are at risk of blood contact through their work (such as healthcare workers), after vaccination because of a needlestick or sexual exposure incident or a partner or household member with hepatitis B, with a weakened immune system or several risk factors for a poor response to vaccination, and if you want to know for yourself whether your vaccination has worked. The best time is 4 to 8 weeks after the last vaccination. In healthy people who are fully vaccinated, the titer is usually protective; a low titer years after vaccination is then normal and does not mean that the protection is gone. Anti-HBs is not a test to show a hepatitis B infection; if you have run a risk, you need HBsAg (and anti-HBc).
Downsides and risks
- A low titer years after a successful vaccination can wrongly give the impression that you are not protected and lead to unnecessary extra vaccinations.
- A protective titer can give false reassurance after a risk contact; an existing infection can only be ruled out with HBsAg and anti-HBc.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results