Clinical Overview of Hepatitis A

Key points

  • Hepatitis A is a highly contagious infection that spreads primarily through fecal-oral transmission.
  • Vaccination is the best way to prevent hepatitis A.
  • Hepatitis A causes an acute infection. It does not become a chronic, long-term infection.
A healthcare professional meeting with a patient in her office


Hepatitis A is one of several viral hepatitis infections that affect the liver. The hepatitis A virus (HAV) causes the infection and is transmitted primarily through the fecal-oral route. A safe and effective vaccine can prevent hepatitis A.

For the general public‎

For people looking for non-clinical information on hepatitis A, visit Hepatitis A Disease Overview


Hepatitis A is a liver infection caused by HAV. It spreads when someone unknowingly ingests the virus through close personal contact with an infected person or by consuming contaminated food or drink.

Risk factors

Although anyone can get hepatitis A, certain people are at a higher risk for infection and serious disease. These people include:

  • International travelers.
  • Men who have sex with men.
  • People who use or inject drugs.
  • People whose jobs increase the risk of exposure.
  • People who anticipate close personal contact with an international adoptee.
  • People experiencing homelessness.

Other conditions can also put people at a higher risk for developing serious disease from an HAV infection, such as chronic liver disease (including hepatitis B and hepatitis C) and human immunodeficiency virus (HIV).

Learn more about at-risk populations and clinical guidelines for addressing all hepatitis strains.

Incubation period

The average incubation period for HAV is 28 days (range: 15–50 days). 123

How it spreads

Hepatitis A is transmitted primarily through the fecal-oral route. This can happen through:

  • Close person-to-person contact with a person who is infected.
  • Sexual contact with a person who is infected.
  • Ingestion of contaminated food or water.

Although HAV can be detected in the blood, bloodborne transmission of HAV is uncommon.

Depending on environmental conditions, the virus can live outside the body for months.4

Infection rates and trends

Hepatitis A isn’t always reported, so infection rates are likely higher than the data indicate. In 2022, 2,265 cases were reported in the United States, but experts estimate the actual number is likely around 4,500.

Since 2016, there have been outbreaks in multiple states caused by person-to-person transmission primarily among people who use drugs and people experiencing homelessness. While there was a 43% decrease in incidence from 2020–2021, the number of cases in 2021 remained four times higher than in 2015.

Mortality rates

In rare cases, hepatitis A can cause liver failure and even death. This is more common in older people and in people with certain serious health issues, such as chronic liver disease.

In 2022, the mortality rate for hepatitis A, based on death certificate listings, was 0.02 per 100,000 people.

The hepatitis A-associated mortality rate in 2022 was highest among persons 65 and older (0.15 deaths per 100,000 people) and among males (0.03 deaths per 100,000 people).

Clinical features

Older children and adults typically experience symptoms when infected with HAV. Symptoms usually occur abruptly and can include the following:

  • Abdominal pain, nausea, and/or vomiting
  • Dark urine or clay-colored stools
  • Diarrhea
  • Fatigue
  • Fever
  • Jaundice
  • Joint pain
  • Loss of appetite

In children younger than 6, 70% of infections are asymptomatic. When symptoms do present, young children typically do not have jaundice, whereas most older children and adults with HAV infection have jaundice.56

Learn more about signs and symptoms of HAV infection.


The best way to prevent infection is by completing the full hepatitis A vaccine series. Immune globulin (IG) can provide short-term protection preexposure, and hepatitis A vaccine and IG can provide protection when administered within 2 weeks after exposure. Learn about additional clinical treatment guidance.

Since HAV is transmitted through the fecal-oral route, encourage your patients to practice good hand hygiene — including handwashing after using the bathroom, changing diapers, and before preparing or eating food.

Vaccination is the best way to prevent HAV infection‎

Testing, screening, and diagnoses

You will not be able to differentiate hepatitis A virus from other types of viral hepatitis using clinical or epidemiological features alone. Clinicians should conduct test(s) to make an accurate diagnosis.

The following are laboratory markers that, if present, indicate an acute HAV infection:

  • Immunoglobulin M antibodies to HAV (IgM anti-HAV) in serum, or
  • HAV RNA in serum or stool8

The following is the serologic marker that, if present, indicates either immunity from prior infection or vaccination:

  • Immunoglobulin G antibodies to HAV (IgG anti-HAV)

Serologic tests for IgG anti-HAV and total anti-HAV (IgM and IgG anti-HAV combined) are not helpful in diagnosing acute illness. You should only test patients for IgM anti-HAV if they are symptomatic, and you suspect HAV infection. Alanine aminotransferase (ALT) and total bilirubin tests can aid in diagnosis.

See detailed testing information for hepatitis A.

Treatment and recovery

Hepatitis A is not a chronic infection. Typically, rest, a balanced diet with healthy food and plenty of fluids are enough to treat the symptoms. In rare cases people with severe symptoms will need to be hospitalized.

Learn more about treating hepatitis A.

Talk to your patients about getting hepatitis A vaccine‎

Getting vaccinated is the best way to prevent hepatitis A.

Patient counseling

Clinicians should talk to their patients about proper treatment, healthy habits, vaccination, transmission prevention, and potential risks.

Learn more about counseling patients with hepatitis A.

Long-term effects

Symptoms of hepatitis A usually last less than 2 months. However, 10%–15% of symptomatic people have a prolonged or relapsing disease for up to 6 months.12347 Unlike other forms of hepatitis, hepatitis A does not become a chronic infection.

Case definitions

To learn more about classification of hepatitis A cases, visit the National Notifiable Diseases Surveillance System (NNDSS).

Content Source:
Division of Viral Hepatitis
  1. Halliday ML, Kang LY, Zhou TK, et al. An epidemic of hepatitis A attributable to the ingestion of raw clams in Shanghai, China. J Infect Dis 1991;164(5):852–9.
  2. Neefe JR, Gellis SS, Stokes J Jr. Homologous serum hepatitis and infectious (epidemic) hepatitis: studies in volunteers bearing on immunological and other characteristics of the etiological agents. Am J Med 1946;1:3–22.
  3. Krugman S, Giles JP, Hammond J. Infectious hepatitis. Evidence for two distinctive clinical, epidemiological, and immunological types of infection. JAMA 1967;200(5):365–73.
  4. Abad FX, Pinto RM, Bosch A. Survival of enteric viruses on environmental fomites. Appl Environ Microbiol 1994;60(10):3704–10.
  5. Gordon SC, Reddy KR, Schiff L, Schiff ER. Prolonged intrahepatic cholestasis secondary to acute hepatitis A. Ann Intern Med 1984;101(5):635.
  6. Schiff ER. Atypical clinical manifestations of hepatitis A. Vaccine 1992;10 Suppl 1:S18-20.
  7. Wasley A, Fiore A, Bell BP. Hepatitis A in the era of vaccination. Epidemiol Rev 2006;28:101–11. Epub 2006 Jun 14. Review.