Lab marker · Low

Low Hepatitis B surface antibody (anti-HBs): what it means

A Hepatitis B surface antibody (anti-HBs) result below the normal range is considered low. Here is what a reduced Hepatitis B surface antibody (anti-HBs) can point to, and when it is worth discussing with a doctor.

Reference range: ≥10 mIU/mL indicates immunity (from vaccination or past infection); <10 mIU/mL means non-immune. Unlike most markers, a HIGH result is the good, protective one

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What a low Hepatitis B surface antibody (anti-HBs) can mean

  • Not immune — no protection has developed; may need (re)vaccination.
  • A non-responder or waned response to the vaccine — some people need an extra course.
  • Never vaccinated or exposed — the expected result before immunisation.

When to discuss with a doctor

Anti-HBs is checked to confirm immunity to hepatitis B — after vaccination (especially in healthcare workers, people on dialysis, or others at risk), or as part of assessing hepatitis B status. A level at or above the threshold is reassuring: it means you are protected. A level below the threshold means you are not currently immune, and vaccination or a booster is usually recommended, guided by your doctor and read together with the other hepatitis B markers. Because this is one of the few tests where a high value is the desirable one, a 'positive' result here is good news. Mediora.AI shows anti-HBs alongside the hepatitis B surface antigen and core antibody so your immunity status is read as a set; decisions about vaccination belong with your doctor.

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Mediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.