Hepatitis B blood tests use a combination of three core markers to tell you whether you’ve never been infected, are currently infected, have recovered, or are immune from vaccination. No single marker gives the full picture. The pattern of positive and negative results across all three markers is what determines your status.
The three markers on a standard hepatitis B panel are HBsAg (surface antigen), anti-HBs (surface antibody), and anti-HBc (core antibody). Here’s what each one means and how they work together.
What Each Marker Tells You
HBsAg (surface antigen) is a protein on the outer shell of the virus. It appears in the blood within 1 to 10 weeks after exposure and is the hallmark of active infection. If HBsAg is positive, the virus is present and you are infectious. If it stays positive for longer than 6 months, the infection is classified as chronic. One exception: HBsAg can show up as a transient positive within 30 days of receiving a hepatitis B vaccine dose, which does not indicate infection.
Anti-HBs (surface antibody) is your immune system’s neutralizing antibody against the virus. It signals protection. A level of 10 mIU/mL or higher is generally considered protective. If you were vaccinated and responded well, this is the only marker that will be positive on your panel. If you recovered naturally from a past infection, anti-HBs will appear alongside anti-HBc.
Anti-HBc (core antibody) targets a protein inside the virus and appears early in infection, about 1 to 2 weeks after HBsAg shows up. The total anti-HBc test measures both IgM and IgG types combined. Once positive, anti-HBc persists for life, so it shows up in people with current infections and in people who cleared the virus years ago. It never turns positive from vaccination alone.
Reading the Results Together
The CDC interpretation framework lays out seven possible combinations. These are the ones you’re most likely to encounter.
All Three Negative
You have never been infected with hepatitis B. If you were never vaccinated, you are susceptible to infection. If you were vaccinated but anti-HBs is undetectable, the vaccine may not have produced a strong enough response.
Only Anti-HBs Positive
This is the classic result for someone successfully vaccinated against hepatitis B. The vaccine teaches your immune system to produce the surface antibody without ever exposing you to the actual virus. Because you were never infected, anti-HBc stays negative.
Anti-HBs and Anti-HBc Both Positive, HBsAg Negative
You were infected with hepatitis B at some point in the past, your immune system cleared the virus, and you are now immune. The anti-HBc is the fingerprint of that past infection, and the anti-HBs confirms your body built lasting protection.
HBsAg and Anti-HBc Positive, Anti-HBs Negative
This pattern indicates a current hepatitis B infection. Whether it’s acute (recent) or chronic (ongoing for more than 6 months) depends on additional testing. If IgM anti-HBc is positive, the infection is recent, typically within the last 6 months. After that window, IgM fades and IgG persists, pointing to chronic infection.
HBsAg Positive, Both Antibodies Negative
This can mean very early acute infection, before the immune system has started producing core antibodies. If HBV DNA testing confirms viral genetic material is present, early infection is the likely explanation. If HBV DNA is negative and you recently received a vaccine dose, it may be a transient false signal from the vaccine itself.
Only Anti-HBc Positive
This isolated result is one of the trickier patterns to interpret. It has four possible explanations: a resolved infection where the surface antibody has faded over time, an occult (hidden) infection where the virus is present at very low levels below the detection limit of standard HBsAg tests, an infection with a mutant virus strain, or simply a false positive lab result. HBV DNA testing helps sort this out. If viral DNA is detectable, the virus is still present. If DNA is undetectable, the most common explanation is a past infection with waning antibody levels.
Acute vs. Chronic Infection
If your results show an active infection (HBsAg positive), the next question is whether it’s acute or chronic. The key test is IgM anti-HBc. A positive IgM result means the infection started within the past 6 months. After about 6 months, IgM fades and only IgG remains. So if HBsAg is still positive and IgM anti-HBc is negative, the infection has become chronic.
This distinction matters because most healthy adults who get an acute hepatitis B infection clear it on their own. Chronic infection, on the other hand, requires ongoing monitoring and may need treatment to prevent liver damage.
Additional Markers for Chronic Infection
If you’re diagnosed with chronic hepatitis B, your provider will likely order additional tests beyond the basic three-marker panel.
HBeAg (e antigen) reflects how actively the virus is replicating. When HBeAg is positive, viral replication is high and you are more infectious. When the immune system begins to control the virus, HBeAg disappears and anti-HBe (e antibody) develops. People who have undergone this shift tend to have significantly lower viral loads.
HBV DNA (viral load) measures the actual amount of virus in your blood. A viral load below 2,000 IU/mL with normal liver enzymes generally defines an inactive carrier state, meaning the virus is present but not actively causing damage. Higher levels, particularly above 20,000 IU/mL, are associated with greater liver disease risk and more likely to prompt treatment discussions. A viral load above 2,000 IU/mL is an independent risk factor for liver cancer regardless of other markers.
ALT (alanine aminotransferase) is a liver enzyme that rises when liver cells are being damaged. Current guidelines from the American Association for the Study of Liver Diseases define the upper limit of normal as 35 U/L for men and 25 U/L for women when making hepatitis B treatment decisions. Persistently elevated ALT combined with a detectable viral load is one of the main triggers for starting antiviral therapy.
Vaccination vs. Natural Immunity
Your results make it straightforward to tell these apart. Vaccine-induced immunity produces only anti-HBs. Natural immunity from a cleared infection produces both anti-HBs and anti-HBc. The core antibody is the dividing line, since the hepatitis B vaccine contains only the surface protein, not the core protein. Your immune system can only make anti-HBc if it has encountered the whole virus.
If you were vaccinated years ago and your anti-HBs has dropped below 10 mIU/mL, that does not necessarily mean you’ve lost protection. Research suggests that immune memory can persist even after antibody levels wane, and a booster dose typically triggers a rapid protective response. However, some guidelines recommend checking anti-HBs levels if you’re in a high-risk group and considering a booster if levels have fallen.
What Occult Hepatitis B Looks Like
Occult hepatitis B is defined as the presence of viral DNA in the blood or liver of someone who tests negative for HBsAg. The virus is there, but at levels too low for the surface antigen test to pick up. Diagnosis requires HBV DNA to be detectable on at least two separate targets in an HBsAg-negative person. Most people with occult hepatitis B have an isolated positive anti-HBc result, though some may have anti-HBs as well. The infection is typically clinically silent but can reactivate if the immune system is suppressed by certain medications or medical conditions.