Hepatitis B serology: reading the panel
A hepatitis B panel is built from three viral antigens and their antibodies. Learn what each marker means and how the combinations separate acute, chronic, recovered and vaccinated patients.
Interpret HBsAg, anti-HBs, HBeAg and anti-HBc IgM and IgG to distinguish acute, chronic and resolved infection and vaccination.
The short version
- HBsAg means current infection, acute or chronic; if it persists beyond 6 months, the infection is chronic.
- Anti-HBs alone means vaccination; anti-HBs plus IgG anti-HBc means recovery from infection.
- IgM anti-HBc marks acute infection, while IgG anti-HBc usually means past infection and often stays for life.
- In the window period HBsAg has gone and anti-HBs has not yet appeared, so anti-HBc, with IgM anti-HBc positive, may be the only serological evidence of infection.
- The vaccine contains only surface antigen, so it never makes core antibody.
What a hepatitis B serology panel measures
Hepatitis B serology is built from three antigen–antibody systems: the surface antigen (HBsAg, part of the viral envelope), the core antigen (HBcAg) and the e antigen (HBeAg). Each has a matching antibody: anti-HBs, anti-HBc and anti-HBe.[1][2]
The puzzle that frames the lesson: two nurses both carry antibody to the surface antigen. One was vaccinated last month and has nothing else. The other recovered years ago and has a second antibody as well. What is the second antibody? The answer comes at the end.
| Marker | What it means |
|---|---|
| HBsAg | Current infection, acute or chronic; the person is infectious[1] |
| Anti-HBs | Immunity |
| HBeAg | Active viral replication and high infectivity |
| Anti-HBe | Replication has fallen |
| IgM anti-HBc | Recent (acute) infection |
| IgG anti-HBc | Infection, usually past, but also present in chronic infection |
HBsAg, HBeAg and the six-month rule
A positive HBsAg means current infection, either acute or chronic, and every HBsAg-positive person is infectious. If HBsAg persists beyond 6 months, spontaneous clearance is unlikely and the infection is chronic.[1]
HBeAg is a protein that circulates in the blood. It correlates with active replication and high infectivity, and its antibody, anti-HBe, correlates with loss of replicating virus.[1][2]
Anti-HBs: the immunity marker
The presence of anti-HBs generally indicates immunity. Measured 1 to 2 months after a complete vaccine series, a level of 10 mIU/mL or more counts as protective.[1][4]
Anti-HBc: IgM versus IgG, and why the vaccine never makes it
Anti-HBc, the core antibody, appears first as IgM, and IgG follows and often stays for life. IgM means recent infection; IgG means infection, usually past, but it is also present in chronic infection. IgM anti-HBc often becomes undetectable within 6 months, while IgG predominates.[1][4]
The hepatitis B vaccine contains only surface antigen. A vaccinated person therefore makes anti-HBs but never core antibody, whereas a person who recovers from natural infection is positive for both anti-HBs and anti-HBc.[1][3]
One acute infection step by step, and the window period
In acute infection HBsAg appears first. One to two weeks later anti-HBc follows, both IgM and IgG.[1]
If the person recovers, HBsAg disappears and anti-HBs develops, typically within 3 to 4 months of infection.[1]
Between those two events lies the window period of hepatitis B: HBsAg has gone, anti-HBs has not yet appeared, and anti-HBc, with IgM anti-HBc positive, may be the only serological evidence of infection.[2][5] Because IgM often fades within 6 months while IgG stays, recovery ends as anti-HBs plus IgG anti-HBc with a negative HBsAg.[1]
- HBsAg appears first.
- 1–2 weeks later: anti-HBc appears (IgM and IgG).
- HBsAg disappears; the window period begins, and anti-HBc (with IgM anti-HBc positive) may be the only serological evidence of infection.
- Typically within 3–4 months of infection: anti-HBs develops, and the window period ends.
- Later: IgM anti-HBc fades, leaving anti-HBs plus IgG anti-HBc, with a negative HBsAg.
Chronic infection and the five hepatitis B serology patterns
In chronic infection, HBsAg persists, anti-HBs is usually absent, and IgM anti-HBc is typically negative.[1][6]
| Pattern | Markers |
|---|---|
| Never infected | All negative |
| Vaccinated | Anti-HBs alone |
| Recovered | Anti-HBs plus IgG anti-HBc, HBsAg negative |
| Chronic | HBsAg plus IgG anti-HBc |
| Acute | HBsAg plus IgM anti-HBc |
Back to the nurses: surface antibody alone is the vaccinated nurse, and surface plus core antibody is the one who recovered.[1]
Practice question
Original · USMLE styleA 29-year-old man has had 5 days of fatigue, nausea and dark urine. Examination shows scleral icterus. Serum ALT is 1850 U/L and total bilirubin is 7.4 mg/dL. HBsAg is negative and anti-HBs is negative. Total anti-HBc and IgM anti-HBc are positive. Hepatitis A IgM and hepatitis C antibody are negative.
Common questions
What does a positive HBsAg mean?
It means current hepatitis B infection, either acute or chronic, and the person is infectious. If HBsAg persists beyond 6 months, the infection is chronic.
How can you tell a vaccinated person from someone who recovered?
A vaccinated person has anti-HBs alone, because the vaccine contains only surface antigen. A person who recovered has anti-HBs plus IgG anti-HBc.
What is the difference between IgM and IgG anti-HBc?
IgM anti-HBc appears first and marks recent infection. IgG anti-HBc follows and often stays for life, so it usually indicates past infection, but it is also present in chronic infection.
What is the window period in hepatitis B?
It is the time between the loss of HBsAg and the appearance of anti-HBs. During it, anti-HBc, with IgM anti-HBc positive, may be the only serological evidence of infection.
What does HBeAg indicate?
HBeAg correlates with active viral replication and high infectivity. Its antibody, anti-HBe, means replication has fallen.
Transcript
Read the full narration, by chapter651 words
0:00Two nurses, one surface antibody: the hook
Two nurses have their blood tested for hepatitis B. One was vaccinated last month, and her blood shows antibody to the surface antigen, and nothing else. The other recovered years ago, and her blood shows that antibody plus a second one. Both carry the surface antibody. What is the second one? Today: read a hepatitis B panel,
0:21What a hepatitis B panel measures
and tell acute, chronic, recovered and vaccinated apart. The panel is built from three viral antigens and their antibodies: surface, core and e.
0:34HBsAg: current infection and the six-month rule
HB s A g, the surface antigen on the envelope, means current infection, acute or chronic, and the person is infectious. Beyond six months, it is chronic.
0:46HBeAg: replication and infectivity
HB e A g, a protein that circulates in the blood, means active replication and high infectivity. Its antibody means replication has fallen. Anti-HB s means immunity.
0:58Anti-HBs: immunity
After vaccination, 10 milli-international units per millilitre or more counts as protective.
1:08Anti-HBc: IgM versus IgG, and the vaccine
Anti-HB c, the core antibody, appears first as I g M, and I g G follows and often stays for life. I g M means recent infection; I g G means infection, usually past, but also present in chronic infection. The vaccine contains only surface antigen, so it never makes core antibody.
1:32One acute infection, step by step
Follow one acute infection. HB s A g appears first, and one to two weeks later anti-HB c follows, both I g M and I g G. If the person recovers, HB s A g disappears, and anti-HB s develops, typically within three to four months.
1:53The window period
Between those two events lies the window period: HB s A g has gone, anti-HB s has not yet appeared, and I g M anti-HB c may be the only positive marker. I g M anti-HB c often fades within six months, but I g G stays. So recovery ends as anti-HB s plus I g G anti-HB c, with a negative HB s A g.
2:21Chronic infection
In chronic infection, HB s A g persists, anti-HB s is usually absent, and I g M anti-HB c is typically negative.
2:31The five patterns, and back to the nurses
Put together: vaccinated, anti-HB s alone. Recovered, anti-HB s plus I g G anti-HB c. Chronic, HB s A g plus I g G anti-HB c. Acute, HB s A g plus I g M anti-HB c. Never infected, nothing. So our nurses: surface antibody alone is the vaccinated one, and surface plus core antibody is the one who recovered.
3:05Your turn: a practice question
Your turn. A 29-year-old man has 5 days of fatigue, nausea and dark urine. He has scleral icterus, ALT of 1850 units per litre, and total bilirubin of 7.4 milligrams per decilitre. HB s A g and anti-HB s are negative. Total anti-HB c and I g M anti-HB c are positive. Hepatitis AI g M and hepatitis C antibody are negative. Which of the following best interprets these results? A, susceptible, with no prior exposure. B, immunity from vaccination. C, acute hepatitis B infection, window period. D, recovery from past infection, with immunity. E, chronic infection. Pause here and decide.
4:03The answer, one option at a time
A is out: a susceptible person has no markers, and he has core antibody. B is out: vaccination gives anti-HB s alone, and he has no anti-HB s. D is out: recovery shows anti-HB s with I g G anti-HB c, and he has no anti-HB s. E is out: chronic infection has a positive HB s A g, and his is negative. So the answer is C. A negative HB s A g and anti-HB s, with positive I g M anti-HB c, is acute hepatitis B in the window period.
4:43Recap pocket card and next lesson
Three things to keep. One: HB s A g means current infection, and beyond six months it is chronic. Two: anti-HB s alone is vaccination; anti-HB s plus I g G anti-HB c is recovery. Three: I g M anti-HB c marks acute infection, and in the window period it may be the only marker. Next, how antifungal drugs work, and the fungal targets they hit.
Sources
Numbers in the text, e.g. [1], point here- Schillie S, et al. Prevention of Hepatitis B Virus Infection in the United States: Recommendations of the Advisory Committee on Immunization Practices (CDC/ACIP). MMWR Recomm Rep 2018. europepmc.org/article/PMC/PMC5837403
- Wikipedia. Hepatitis B. en.wikipedia.org/wiki/Hepatitis_B
- Wikipedia. Hepatitis B vaccine. en.wikipedia.org/wiki/Hepatitis_B_vaccine
- Europe PMC. Anti-HBs threshold and isolated anti-HBc. europepmc.org/article/PMC/PMC13415320
- Europe PMC. IgM anti-HBc in acute hepatitis B. europepmc.org/article/PMC/PMC13343972
- Europe PMC. Chronic hepatitis B with low-titre anti-HBs (case report). europepmc.org/article/PMC/PMC13220585
The practice question is original and its patient is synthetic. Every fact is checked against the sources above in independent accuracy reviews. Always follow your local guidelines and your own laboratory’s ranges.
Image credits. Illustrations: Servier Medical Art (smart.servier.com), CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/), adapted (recoloured, outlined, resized): blood tube, syringe, hepatitis B virion. Illustration: NIAID NIH BioArt Source (bioart.niaid.nih.gov), public domain, adapted: vaccine vial (BioArt item 534). Icons: Health Icons (healthicons.org), CC0 (nurse, person). The antibodies, antigens, marker strip, time-course graph, table, question card, recap and all handwriting are drawn in code (original). No AI-generated teaching images.
Corrections. None so far. Spotted an error? Email info@medservatory.com with the lesson code MS-S1-MICRO-011.
For exam study only, not medical advice. Read the medical disclaimer.
In this series
Playlist on YouTube- EP 01Gram-positive vs gram-negative cell walls5:39
- EP 02Acid-fast stain and the mycobacterial cell wall5:01
- EP 03Endotoxin vs exotoxin: lipid A, A-B toxins and toxoids5:46
- EP 04Bacterial toxins that raise cAMP: cholera, pertussis, anthrax5:54
- EP 05Clostridial toxins compared: tetanus, botulinum, alpha, C. difficile5:22
- EP 06Staph vs strep: catalase, coagulase and haemolysis5:23
- EP 07Encapsulated organisms and the spleen: asplenia and conjugate vaccines5:08
- EP 08Bacterial genetics: how bacteria swap genes5:13
- EP 09Beta-lactamase and antibiotic resistance: three ways bacteria win5:13
- EP 10DNA vs RNA virus replication: which enzyme each genome needs5:48
- EP 11HIV life cycle and drug targets, step by step5:39
- EP 12Hepatitis B serology: reading the panel5:17
- EP 13Antifungal drugs explained: mechanisms of action5:26
- EP 14Bacterial meningitis organisms by age and risk group5:19