Hepatitis A vs. B: Transmission, Prevention, Clinical Features & Vaccination

Hepatitis A (HAV) and Hepatitis B (HBV) are distinct viruses causing liver inflammation. While both can cause acute hepatitis, their transmission routes, chronicity, and prevention strategies differ significantly.

Comparison at a Glance

Feature	Hepatitis A (HAV)	Hepatitis B (HBV)
Virus Family	Picornaviridae (RNA)	Hepadnaviridae (DNA)
Primary Transmission	Fecal-oral: contaminated food/water, close personal contact, sexual (MSM)	Blood/body fluids: perinatal, sexual, percutaneous (needles, transfusions), horizontal (childhood in endemic areas)
Chronic Infection	Never (acute only)	Yes: 90% infants, 25–50% children 1–5y, <5% adults → cirrhosis, HCC
Incubation	15–50 days (avg 28)	60–150 days (avg 90)
Clinical Course	Acute hepatitis; fulminant rare (<1%); relapsing 10–15%	Acute (often asymptomatic adults); chronic carrier state; reactivation
Vaccine	Inactivated (Havrix, Vaqta): 2-dose series (0, 6–12 mo); ≥95% efficacy	Recombinant HBsAg (Engerix-B, Recombivax HB): 3-dose (0, 1, 6 mo); >95% efficacy. Heplisav-B: 2-dose (0, 1 mo).
Post-Exposure Prophylaxis	Vaccine ± IG (0.1 mL/kg) within 2 weeks	HBIG + Vaccine (within 24h birth/perinatal; 7d percutaneous; 14d sexual)
Treatment	Supportive only	Acute: supportive. Chronic: Nucleos(t)ide analogs (TAF, TDF, ETV) – suppress, rarely cure.

Shared Prevention Strategies

• Vaccination: Universal childhood (HAV: 12–23 mo; HBV: birth dose + series). Catch-up for unvaccinated adults with risk factors.
• Harm Reduction: Needle exchange, safe injection sites, condom use.
• Screening: HBV: All adults ≥18 once (HBsAg, anti-HBc, anti-HBs); pregnant women (HBsAg); high-risk periodic.
• Hygiene: Handwashing, safe food/water (HAV); avoid sharing razors/toothbrushes (HBV).

High-Risk Groups for Vaccination

• HAV: Travelers to endemic areas, MSM, PWID, chronic liver disease, homeless, adoptees from endemic countries.
• HBV: Healthcare workers, dialysis patients, HIV/HCV coinfection, incarcerated, sexual contacts of HBsAg+, diabetes <60, travelers to high-endemic regions.

Key Takeaway

Both are vaccine-preventable. HAV is acute, fecal-oral, never chronic. HBV is blood/fluid-borne, establishes chronic infection in a significant minority, leading to cirrhosis and hepatocellular carcinoma. Universal vaccination has dramatically reduced incidence in immunized cohorts. Know your status. Get vaccinated.