Viral Hepatitis A, B & C

Clinical Case

A 36-year-old woman, originally from Vietnam, is referred for evaluation of elevated ALT (82 IU/L) found on routine pre-employment bloodwork. She is asymptomatic and feels well. She has never received the hepatitis B vaccine. Her mother had cirrhosis, etiology unknown. Exam is unremarkable.

HBsAg: POSITIVE · Anti-HBs: negative · Anti-HBc (total): POSITIVE · HBeAg: negative · Anti-HBe: POSITIVE · HBV DNA: 1,200 IU/mL · ALT: 82 IU/L · AST: 58 IU/L

Work through the management step by step before the answers are revealed.

HAV is a picornavirus (ssRNA) transmitted by the fecal-oral route — contaminated water and food (especially shellfish), travel to endemic areas, household contact, men who have sex with men (MSM), and persons who inject drugs (PWID).

Key clinical point: HAV NEVER causes chronic infection. Acute illness resolves in 1–3 months. Rarely (~0.5%) causes fulminant hepatic failure — risk is elevated in patients with pre-existing chronic liver disease (case fatality ~1.5–2% in chronic viral hepatitis; higher in decompensated cirrhosis). Note: the markedly higher mortality figures (~30–35%) reported in some series reflect hepatitis E superinfection on chronic liver disease, not hepatitis A.

Feature	Hepatitis A
Virus family	Picornavirus (ssRNA)
Transmission	Fecal-oral (contaminated food/water, shellfish, travel, MSM, PWID)
Incubation	~28 days (range 15–50 days)
Chronic infection	Never — HAV is always self-limiting
Fulminant hepatic failure	<0.5% overall; elevated in pre-existing chronic liver disease (~1.5–2% case fatality in chronic viral hepatitis; higher in decompensated cirrhosis). The 30–35% mortality figures in the literature reflect hepatitis E, not A, superinfection.
Diagnosis	Anti-HAV IgM (acute/recent); Anti-HAV IgG or total anti-HAV (immunity — prior infection or vaccine)
Treatment	Supportive; avoid hepatotoxins and alcohol; isolation; report to public health
Prevention	2-dose vaccine (Havrix 1440 U or Vaqta 50 U, 6–12 months apart); immunity is lifelong post-vaccination

Serology in 60 Seconds

Anti-HAV IgM = current acute infection (appears at onset of symptoms, persists ~6 months). Anti-HAV IgG = prior infection or successful vaccination. A positive total anti-HAV with a negative IgM = past exposure or vaccinated = immune. A negative total anti-HAV = susceptible = vaccinate.

Patients with cirrhosis, chronic hepatitis B, or chronic hepatitis C who contract HAV have dramatically higher mortality. Vaccination is therefore recommended in all patients with chronic liver disease.

Quick recall

HAV serology shows anti-HAV IgM positive and anti-HAV IgG negative. What does this tell you?

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Acute hepatitis A — early infection before IgG has developed.

IgM appears at symptom onset and peaks in the first 1–2 weeks. IgG develops 2–3 weeks into illness and persists for life. A rising IgG with declining IgM signals convalescence.

Vaccinate immediately — HAV in the setting of chronic liver disease carries elevated mortality (~1.5–2% case fatality in chronic viral hepatitis; significantly higher in decompensated cirrhosis). Vaccination is safe and highly effective in CLD.

All patients with chronic liver disease who are HAV seronegative should receive the 2-dose HAV vaccine regardless of travel plans. Check anti-HAV IgG first — if already immune (prior infection), no vaccine needed.

A patient with cirrhosis from MASLD is planning a trip to India. What is your hepatology-specific recommendation?

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HBV is a DNA hepadnavirus transmitted parenterally (needlestick, injection drug use), sexually, and perinatally (mother-to-child during delivery). Perinatal transmission accounts for the majority of the global HBV burden, particularly in sub-Saharan Africa and East Asia.

	Adults	Neonates/Infants
Acute HBV	Self-limiting in ~95%	Progress to chronic in ~90%
Chronicity	~5% develop chronic HBV	~90% become chronically infected
Why the difference	Mature immune response clears the virus	Immature immune tolerance; cccDNA established early

The Most Confusing Test in Hepatology

Anti-HBc (core antibody) is NOT produced after vaccination — it only appears after natural infection. Vaccination produces only anti-HBs. This distinction has major clinical significance: anti-HBc+, anti-HBs+, HBsAg- = resolved natural infection (not vaccination).

Serologic Patterns — Interactive Interpreter

Select a serologic pattern

Quick recall

Which hepatitis B serologic marker indicates natural infection but is NOT produced by vaccination?

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Anti-HBc (antibody to core antigen)

Vaccination with HBV surface antigen subunit vaccine only induces anti-HBs. Anti-HBc is only produced during natural infection when the full virus replicates and core antigen is expressed. Its presence always indicates prior natural exposure.

What is the significance of IgM anti-HBc positivity?

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Acute hepatitis B — distinguishes acute from chronic infection

In chronic HBV, anti-HBc shifts to IgG class over months. In acute HBV, IgM anti-HBc is positive and persists for 3–6 months. This test is critical in diagnosing acute HBV when HBsAg is already detectable.

Check HBV DNA; start HBV antiviral prophylaxis — occult HBV reactivation risk is high with anti-CD20 therapy.

Anti-CD20 agents (rituximab) carry >10% overall risk of HBV reactivation in anti-HBc positive patients — stratified by anti-HBs titer: ~27% if anti-HBs negative, ~14% if anti-HBs 10–100 IU/L, ~4% if anti-HBs >100 IU/L (PMID 41390946). AASLD and ASCO recommend antiviral prophylaxis (entecavir or tenofovir) before starting immunosuppression in all anti-HBc positive patients regardless of anti-HBs status.

An oncology patient is starting rituximab. HBsAg is negative but anti-HBc is positive. What must happen before starting?

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Check HBV DNA; start HBV antiviral prophylaxis — occult HBV reactivation risk is high with anti-CD20 therapy.

Goals of treatment: suppress HBV DNA to undetectable → halt fibrosis progression → prevent cirrhosis and HCC → prevent liver failure.

HBsAg stays positive throughout chronic infection (until HBsAg loss). Not every patient passes through all phases, and an indeterminate "grey-zone" also exists. DNA in IU/mL.

HBV Phase (2025 AASLD-IDSA)	HBV DNA	ALT / Fibrosis	2025 Recommendation
HBeAg+ immune-active (ALT ≥2×ULN + high DNA)	≥20,000 IU/mL	Elevated (≥2×ULN)	Treat — TAF, TDF, or ETV
HBeAg+ immune-tolerant, age >40 yr (or ≥A2 inflammation / ≥F2 fibrosis)	Very high (≥10⁷ IU/mL)	Normal	Treat — new 2025 recommendation; prior 2018 guidance was observe-only
HBeAg+ immune-tolerant, age ≤40 yr, no significant fibrosis	Very high (≥10⁷ IU/mL)	Normal	Shared decision-making; monitor q3–6 months; treat if ≥F2
HBeAg-negative immune-active	≥2,000 IU/mL	ALT ≥2×ULN (or ≥F2 fibrosis)	Treat — TAF, TDF, or ETV
Inactive CHB (HBeAg-negative)	<2,000 IU/mL	Normal	Monitor every 6–12 months; no treatment unless DNA rises or fibrosis present
Any phase + cirrhosis	Any detectable	Any	Treat regardless of ALT or HBV DNA level
Pre-immunosuppression (HBsAg+ or anti-HBc+)	Any / occult	—	Antiviral prophylaxis before starting immunosuppression
Indeterminate/grey zone	Variable (often 2,000–20,000)	Borderline or mildly elevated	Fibrosis staging ± biopsy; treat if ≥F2; individualize if minimal fibrosis

2025 AASLD-IDSA — Key Changes from 2018

The 2025 AASLD-IDSA guideline (Ghany et al., Hepatology 2026;83:974–997, PMID 41186418) retains the classic phase names (immune-tolerant, immune-active, inactive, indeterminate) and updates several management points: (1) Immune-tolerant patients (HBeAg-positive, HBV DNA ≥10⁷ IU/mL, normal ALT) are now suggested for treatment if over age 40, or with grade ≥2 (≥A2) inflammation or ≥F2 fibrosis — previously observe-only. (2) HBeAg-negative patients in the indeterminate ("grey zone") phase may now be treated via shared decision-making. (3) Immune-active treatment thresholds are unchanged from 2018: HBeAg-positive requires HBV DNA ≥20,000 IU/mL with ALT ≥2×ULN; HBeAg-negative requires HBV DNA ≥2,000 IU/mL with ALT ≥2×ULN. (4) In HBeAg-negative, non-cirrhotic patients with sustained viral suppression, nucleos(t)ide analogue therapy should not be withdrawn until HBsAg loss.

Agent	Dosing	Barrier to Resistance	Key Notes
Entecavir (ETV)	0.5 mg daily (1 mg if lamivudine-experienced)	High	Preferred first-line; well tolerated; do not use if lamivudine resistance — cross-resistance
Tenofovir alafenamide (TAF)	25 mg daily	High	Preferred with renal insufficiency or osteoporosis risk; lower renal and bone side effects than TDF
Tenofovir disoproxil fumarate (TDF)	300 mg daily	High	Effective, low cost, widely used; monitor renal function and bone density long-term
Pegylated interferon alfa-2a	180 µg SQ weekly × 48 weeks	N/A (finite course)	Finite treatment option; ~32% HBeAg seroconversion rate in predominantly Asian genotype B/C cohorts (Lau 2005, PMID 15987917); ~27% in Western genotype A/D populations; more side effects (flu-like, cytopenia, psychiatric); contraindicated in cirrhosis with portal hypertension

Indeterminate anti-HBc with Normal HBsAg — Reactivation Risk

Always screen with HBsAg + anti-HBc before starting: corticosteroids (>10 mg prednisone equivalent × >4 weeks), rituximab, TNF-α inhibitors, checkpoint inhibitors, or chemotherapy. HBV reactivation can be life-threatening and is preventable.

Quick recall

Why is lamivudine no longer first-line for HBV?

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High rate of resistance mutations (YMDD motif) — ~25% per year, >70% at 5 years

Lamivudine monotherapy selects for mutations in the polymerase YMDD motif, leading to viral breakthrough. Entecavir and tenofovir have high genetic barriers with resistance rates <1% over 5+ years.

After HBeAg seroconversion is confirmed PLUS an additional 12 months of consolidation therapy

HBeAg seroconversion is not sufficient alone — viral relapse is common if treatment stops immediately. AASLD recommends at least 12 months of continued therapy after confirmed seroconversion (anti-HBe development + persistent HBV DNA suppression). Indefinite treatment is recommended for HBeAg-negative CHB and all cirrhotics.

A patient with chronic HBV achieves HBeAg seroconversion on entecavir after 18 months. When can therapy stop?

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After HBeAg seroconversion is confirmed PLUS an additional 12 months of consolidation therapy

HCV is an ssRNA flavivirus transmitted almost exclusively parenterally — injection drug use is the dominant route in the US. Blood transfusions before 1992 (pre-screening era) were a major historical source. Sexual and perinatal transmission occur but are less efficient than HBV.

Feature	Hepatitis C
Virus	Flavivirus (ssRNA); 6 major genotypes
Dominant US genotype	Genotype 1a/1b (~70% of US cases)
Most aggressive genotype	Genotype 3 — highest risk for hepatic steatosis, rapid fibrosis, and HCC even without cirrhosis
Primary transmission	Injection drug use (IVDU/PWID); blood transfusions pre-1992; needlestick; perinatal; sexual (lower risk)
Spontaneous clearance	~15–25% of acutely infected persons clear HCV within 6 months (varies by sex, IL28B genotype, and HIV status; higher estimates in some cohorts)
Chronic infection	~70–80%; most asymptomatic for decades
Cirrhosis risk	~10–20% of chronic HCV develop cirrhosis over 20–30 years in population-based series; higher (~20–30%) in clinic/referred populations with ascertainment bias (Westbrook & Dusheiko, PMID 25443346)
HCC risk (cirrhotic)	2–4% per year in untreated cirrhosis; post-SVR the risk reduces to ~1–2%/year but persists — HCC surveillance should continue indefinitely in all cirrhotics regardless of SVR (Westbrook & Dusheiko, J Hepatol 2014, PMID 25443346)
No chronic infection marker	Unlike HBV, there is no equivalent of "anti-HBs" to confirm cure — must measure HCV RNA

Diagnostic Algorithm

Step 1 — Screen with anti-HCV antibody (EIA/ELISA): indicates prior exposure (current or past). Stays positive for life even after clearance or successful treatment. Cannot distinguish active from resolved infection.

Step 2 — Confirm active infection with HCV RNA (PCR): detects viral RNA; confirms current viremia. Use quantitative HCV RNA for baseline viral load; combine with genotype testing.

Anti-HCV	HCV RNA	Interpretation
Negative	Not needed	No HCV exposure; repeat if high risk or recent exposure (window period ~8 weeks for antibody)
Positive	Positive	Active HCV infection — stage fibrosis (FIB-4, FibroScan) and treat
Positive	Negative	Prior HCV exposure, now resolved (spontaneously cleared OR successfully treated). Not currently infectious. Antibody stays positive permanently.
Negative	Positive (rare)	Acute HCV before antibody develops, OR immunocompromised patient who cannot mount antibody response. If clinical suspicion high, check RNA regardless.

Reflex HCV RNA testing: Many health systems now automatically reflex to HCV RNA if anti-HCV is positive — this single lab draw allows same-day diagnosis of active infection.

Do Genotypes Still Matter?

Pre-2016, HCV genotype was essential to select treatment. With pan-genotypic DAA regimens (SOF/VEL, G/P), genotyping is no longer required for selecting first-line therapy in most patients. However, it remains useful in treatment-experienced patients, genotype 3 with cirrhosis (requires modified regimen), and in resource-limited settings.

Quick recall

A patient treated for HCV 3 years ago tests anti-HCV positive. Does this mean treatment failed?

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Not necessarily — anti-HCV remains positive for life after exposure, including after successful treatment.

The anti-HCV antibody does not distinguish cured from active infection. Check HCV RNA to determine if the patient has active viremia. If HCV RNA is undetectable 12+ weeks after treatment end, SVR is confirmed = cured.

What is the window period for HCV antibody testing after exposure?

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~8–11 weeks for antibody detection; HCV RNA detectable within 1–2 weeks of infection

If a needlestick or other high-risk exposure has occurred recently (<8 weeks), a negative anti-HCV does not rule out infection — order HCV RNA directly. For needlestick follow-up, many centers check HCV RNA at 3–6 weeks post-exposure.

SVR (sustained virologic response) = HCV RNA undetectable at 12 weeks after completing treatment = functional cure in >97–99% of cases. Modern DAA regimens achieve SVR in >95% of all patients with minimal side effects.

The DAA Revolution

Before 2013, HCV treatment required 24–48 weeks of pegylated interferon + ribavirin with SVR rates of 40–50% for genotype 1 (dominant in the US and Western Europe) and 70–80% for genotypes 2 and 3, along with significant side effects (flu-like symptoms, anaemia, neuropsychiatric effects). Pan-genotypic oral DAAs (approved 2016–2017) transformed HCV into a curable disease with 8–12 week oral regimens and SVR rates exceeding 95% across all patient populations.

SOF/VEL (Epclusa)

Sofosbuvir/Velpatasvir

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G/P (Mavyret)

Glecaprevir/Pibrentasvir

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Patient Profile	SOF/VEL Duration	G/P Duration
Treatment-naive, no cirrhosis, GT1–6	12 weeks	8 weeks
Compensated cirrhosis, GT1–6	12 weeks (+ RBV if GT3)	12 weeks
Decompensated cirrhosis	12 weeks + ribavirin (SOF-based)	Contraindicated
Treatment-experienced (IFN/RBV)	12 weeks	12 weeks
Prior NS5A inhibitor failure	SOF/VEL/VOX (triple) × 12 weeks	Not recommended

Check Drug Interactions Before Treating

DAAs interact with common medications: rifampin (dramatically lowers DAA levels — contraindicated); HIV antiretrovirals (check specific combination); statins (rosuvastatin can reach toxic levels with G/P — hold); acid-reducing agents (separate dosing by 4h with SOF/VEL). Use hcvguidelines.org or Liverpool Drug Interactions checker.

Cured ≠ No Further Risk

After SVR, HCV RNA becomes undetectable. However: (1) Cirrhosis does NOT reverse after SVR — continue HCC surveillance (ultrasound ± AFP every 6 months) indefinitely in cirrhotics. (2) Fibrosis improves over years but portal hypertension and variceal risk persist. (3) Reinfection is possible in patients with ongoing IVDU — retest HCV RNA annually if risk factors persist. (4) HCV antibody remains positive permanently — do not use it to assess cure.

Quick recall

What does SVR mean, and how is it confirmed?

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SVR = HCV RNA undetectable at 12 weeks post-treatment end — a functional cure. Confirmed with a quantitative HCV RNA assay at week 12 after the last dose.

SVR12 has >99% durability — fewer than 1% of patients with SVR12 experience late relapse. SVR24 (used in early trials) is considered equivalent and no longer required for standard practice.

Add weight-based ribavirin to the 12-week SOF/VEL regimen (or use G/P × 12 weeks as alternative).

GT3 is the most difficult genotype to treat, particularly with cirrhosis. NS5A resistance polymorphisms in GT3 reduce the activity of velpatasvir. In GT3 cirrhotics, SOF/VEL alone achieves approximately 86–91% SVR (real-world and subgroup data); adding weight-based ribavirin pushes SVR to >95% in this subgroup. Current AASLD/EASL guidance recommends SOF/VEL + RBV × 12 weeks for GT3 with compensated cirrhosis.

A patient with HCV genotype 3 and cirrhosis is starting SOF/VEL. What modification is required?

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Add weight-based ribavirin to the 12-week SOF/VEL regimen (or use G/P × 12 weeks as alternative).

G/P achieved SVR. Six months later, the patient's anti-HCV is positive on repeat testing. What does this mean?

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Expected finding — anti-HCV remains positive for life after exposure, regardless of SVR. Confirm cure with HCV RNA (should be undetectable).

The anti-HCV antibody persists permanently and is not a marker of active infection. Only HCV RNA confirms active viremia. This is a common point of confusion.

Vaccine	Series	Indications	Post-Vaccination Check
Hepatitis A (Havrix / Vaqta)	2-dose: 0, 6–12 months	Travel to endemic areas, chronic liver disease, MSM, PWID, persons experiencing homelessness, household contacts of acute HAV, all children ≥12 months	Not routinely required — seropositivity >94%
Hepatitis B (Engerix-B / Recombivax-HB)	3-dose: 0, 1, 6 months	All adults ≤60 (ACIP 2022); adults >60 at provider discretion; healthcare workers; all infants (universal at birth)	Check anti-HBs 1–2 months after series; ≥10 mIU/mL = immune; non-responders: repeat series or Heplisav-B
Hepatitis B (Heplisav-B)	2-dose: 0, 1 month	Same indications; preferred in adults who need faster immunity (pre-procedure, immunocompromised)	Check anti-HBs 1–2 months after 2nd dose
Combined HAV/HBV (Twinrix)	3-dose: 0, 1, 6 months	Patients who need both HAV and HBV vaccination; simplifies schedule	Check anti-HBs 4–8 weeks post-series

HBV Post-Exposure Prophylaxis (PEP)

Needlestick or mucous membrane exposure from an HBsAg-positive source: (1) HBIG (hepatitis B immune globulin) 0.06 mL/kg IM as soon as possible (ideally within 12–24 hours; CDC recommends within 24 hours for percutaneous exposure). (2) HBV vaccine series, first dose within 12–24 hours at a separate site. Together, PEP is >90% effective if given promptly.

USPSTF 2020 — HCV Screening

The US Preventive Services Task Force (2020) recommends screening for HCV in ALL adults aged 18–79 years (Grade B recommendation). One-time testing is recommended; annual testing is recommended for persons with ongoing risk factors (IVDU, HIV, incarceration). HCV screening is critical: most people with chronic HCV are unaware of their infection.

No HCV vaccine exists. Harm reduction is the primary prevention strategy: needle and syringe programs (NSPs), opioid agonist therapy (methadone, buprenorphine), single-use medical equipment, and universal precautions. Pre-exposure or post-exposure prophylaxis is not available for HCV.

Quick recall

An unvaccinated healthcare worker sustains a needlestick from a patient known to be HBsAg positive. What must happen within the next 12–24 hours?

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HBIG 0.06 mL/kg IM + first dose of HBV vaccine, at separate injection sites

HBIG provides immediate passive immunity. The vaccine series provides active long-term immunity. Together they reduce transmission risk by >90% if given within 24 hours. Time is critical — efficacy decreases significantly after 24 hours.

Yes — USPSTF (2020) recommends one-time HCV screening for all adults aged 18–79 regardless of risk factors.

Most people with chronic HCV are asymptomatic for decades. Universal screening (not risk-based) was adopted because risk-factor-based screening missed a substantial proportion of infected individuals. The test is simple (anti-HCV antibody), treatment is curative, and early treatment prevents cirrhosis and HCC.

A 45-year-old woman comes for a routine wellness visit. She has no liver symptoms and no known risk factors. Should you screen for HCV?

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Yes — USPSTF (2020) recommends one-time HCV screening for all adults aged 18–79 regardless of risk factors.