Our Vaccine Update “Fast Facts” series continues this month with a focus on hepatitis A. Unlike hepatitis B and C, which are transmitted mainly through contact with blood and body fluids, hepatitis A is primarily transmitted when people ingest food or water contaminated with the virus. People can also get infected after handling or being exposed to the feces of an infected individual, such as through insufficient handwashing or in settings with limited sanitation. Recommendations for vaccination, including universal vaccination of children, have led to dramatic declines in disease in the U.S. However, outbreaks continue to occur, especially in under-immunized communities and among adults with certain risk factors.
As of 2023, the estimated number of new hepatitis A infections in the U.S. was about 3,300, a sharp decline compared with the large outbreaks of the previous decade. More recent outbreaks have been concentrated among people experiencing homelessness, those who use drugs, and communities with limited access to sanitation or vaccination. For example, Florida has reported new cases each month in early 2025, largely in unvaccinated individuals, and Los Angeles County declared a community-wide outbreak with about 165 cases since 2024. Importantly, many of the Los Angeles cases have been among people without known risk factors. Additionally, contamination of specific food products, such as fresh and frozen strawberries, have led to sporadic outbreaks. Green onions, pomegranate arils, and even imported scallops have all been implicated in prior outbreaks.
Although more attention is often paid to other vaccine-preventable diseases, it’s important to continue with diligent hepatitis A vaccine administration to sustain our success.
Recognizing hepatitis A
Hepatitis A is a viral infection that causes irritation and inflammation of the liver. Patients experience fatigue, abdominal pain, nausea, vomiting, dark urine, and yellowing of the eyes and skin (jaundice). Symptoms may last for weeks to months. Children younger than 6 years of age often have mild or asymptomatic infections, but older children and adults tend to develop jaundice and clinically apparent illness. Though hepatitis A does not cause chronic infection, like hepatitis B and C, people can become sick enough to require hospitalization. In rare cases, infection can lead to fulminant liver failure that can be fatal. Fulminant liver disease tends to occur more often among older adults or people with underlying liver disease.
Though hepatitis A is classically a liver disease, it can trigger effects outside of the liver, such as rash and joint aches. It can also cause rare immune-mediated complications, like:
- Hemolytic anemia, a condition characterized by low red blood cells due to premature cell destruction
- Guillain-Barré syndrome, a condition in which the immune system attacks the nervous system
- Glomerulonephritis, an inflammation of the filters of the kidneys
Making a hepatitis A diagnosis
Laboratory testing is needed when a clinician suspects hepatitis A based on the above symptoms. Serologic testing for IgM anti-hepatitis A (anti-HAV) antibodies is the standard diagnostic method. IgM antibodies can usually be measured at the start of symptoms and up to six months thereafter. Unlike hepatitis B or C, molecular testing by PCR is not typically part of routine testing, though it may be used in rare cases to help interpret questionable IgM results. Clinicians should be aware that IgM results can occasionally be falsely positive, particularly in individuals with other viral infections.
All cases of hepatitis A need to be reported to health departments for ongoing surveillance, as this allows officials to identify outbreaks and investigate sources of infection.
Treatment and management of hepatitis A
No specific antiviral therapy exists for hepatitis A. Management is supportive and focuses on rest, ensuring the patient is well hydrated, and symptom relief, such as reducing nausea or abdominal pain. Most patients recover fully within weeks to months, though 10%-15% of people may have symptoms that come and go over several months. Hospitalization for hydration may be required for severe cases, especially in older adults or individuals with underlying liver disease.
Long-term impacts
Unlike hepatitis B or C, hepatitis A does not cause chronic infection. However, acute illness can be prolonged, and, in rare cases, it can lead to fulminant hepatic failure.
Infection control: Reducing the spread of hepatitis A
Hepatitis A spreads through food and water contaminated with feces (e.g., improperly washed food or spread from infected food-preparation staff), living in unsanitary conditions or from close personal contact, such as by caring for someone infected with the virus. Hepatitis A virus is remarkably stable; it can survive on surfaces for weeks, withstand freezing, and resist inactivation by some disinfectants. Standard alcohol hand sanitizers are less effective, so thorough handwashing with soap and water is critical and required to reduce spread.
People are most infectious in the one to two weeks prior to the onset of jaundice, when the amount of virus in their feces is at its peak. This means they may transmit the virus before realizing they are ill, contributing to more stealthy spread. Child care workers may be exposed to dirty diapers without knowing the child is infected, and food preparation workers with inadequate hand hygiene may prepare meals for many without being aware of their illness. Outbreaks have been traced to restaurants, child care centers, correctional facilities, and communities with limited sanitation.
Post-exposure prophylaxis with either hepatitis A vaccine or immune globulin is recommended for unvaccinated individuals who have been exposed in the past two weeks. The vaccine is generally preferred for healthy individuals 12 months through 40 years of age, while immune globulin is used in infants. Healthy adults over 40 can use vaccine or immune globulin. Those who are immunocompromised or have chronic liver disease should receive both.
Hepatitis A: Key clinical takeaways
Although hepatitis A is less common in the U.S. than in the past, outbreaks continue to occur, often in under-immunized adult populations. Providers should consider hepatitis A in patients with compatible illness, particularly if they have a history of recent travel, drug use, homelessness, or exposure to known outbreaks. Vaccination remains the most effective preventive measure and should be reviewed during both pediatric and adult visits.
Resources for families
- Hepatitis A: The Diseases & Vaccines (webpage)
- Vaccines on the Go: What You Should Know (mobile app)
- Why do Babies Get the Hepatitis A Vaccine? (video)
Resources for providers
Our Vaccine Update “Fast Facts” series continues this month with a focus on hepatitis A. Unlike hepatitis B and C, which are transmitted mainly through contact with blood and body fluids, hepatitis A is primarily transmitted when people ingest food or water contaminated with the virus. People can also get infected after handling or being exposed to the feces of an infected individual, such as through insufficient handwashing or in settings with limited sanitation. Recommendations for vaccination, including universal vaccination of children, have led to dramatic declines in disease in the U.S. However, outbreaks continue to occur, especially in under-immunized communities and among adults with certain risk factors.
As of 2023, the estimated number of new hepatitis A infections in the U.S. was about 3,300, a sharp decline compared with the large outbreaks of the previous decade. More recent outbreaks have been concentrated among people experiencing homelessness, those who use drugs, and communities with limited access to sanitation or vaccination. For example, Florida has reported new cases each month in early 2025, largely in unvaccinated individuals, and Los Angeles County declared a community-wide outbreak with about 165 cases since 2024. Importantly, many of the Los Angeles cases have been among people without known risk factors. Additionally, contamination of specific food products, such as fresh and frozen strawberries, have led to sporadic outbreaks. Green onions, pomegranate arils, and even imported scallops have all been implicated in prior outbreaks.
Although more attention is often paid to other vaccine-preventable diseases, it’s important to continue with diligent hepatitis A vaccine administration to sustain our success.
Recognizing hepatitis A
Hepatitis A is a viral infection that causes irritation and inflammation of the liver. Patients experience fatigue, abdominal pain, nausea, vomiting, dark urine, and yellowing of the eyes and skin (jaundice). Symptoms may last for weeks to months. Children younger than 6 years of age often have mild or asymptomatic infections, but older children and adults tend to develop jaundice and clinically apparent illness. Though hepatitis A does not cause chronic infection, like hepatitis B and C, people can become sick enough to require hospitalization. In rare cases, infection can lead to fulminant liver failure that can be fatal. Fulminant liver disease tends to occur more often among older adults or people with underlying liver disease.
Though hepatitis A is classically a liver disease, it can trigger effects outside of the liver, such as rash and joint aches. It can also cause rare immune-mediated complications, like:
- Hemolytic anemia, a condition characterized by low red blood cells due to premature cell destruction
- Guillain-Barré syndrome, a condition in which the immune system attacks the nervous system
- Glomerulonephritis, an inflammation of the filters of the kidneys
Making a hepatitis A diagnosis
Laboratory testing is needed when a clinician suspects hepatitis A based on the above symptoms. Serologic testing for IgM anti-hepatitis A (anti-HAV) antibodies is the standard diagnostic method. IgM antibodies can usually be measured at the start of symptoms and up to six months thereafter. Unlike hepatitis B or C, molecular testing by PCR is not typically part of routine testing, though it may be used in rare cases to help interpret questionable IgM results. Clinicians should be aware that IgM results can occasionally be falsely positive, particularly in individuals with other viral infections.
All cases of hepatitis A need to be reported to health departments for ongoing surveillance, as this allows officials to identify outbreaks and investigate sources of infection.
Treatment and management of hepatitis A
No specific antiviral therapy exists for hepatitis A. Management is supportive and focuses on rest, ensuring the patient is well hydrated, and symptom relief, such as reducing nausea or abdominal pain. Most patients recover fully within weeks to months, though 10%-15% of people may have symptoms that come and go over several months. Hospitalization for hydration may be required for severe cases, especially in older adults or individuals with underlying liver disease.
Long-term impacts
Unlike hepatitis B or C, hepatitis A does not cause chronic infection. However, acute illness can be prolonged, and, in rare cases, it can lead to fulminant hepatic failure.
Infection control: Reducing the spread of hepatitis A
Hepatitis A spreads through food and water contaminated with feces (e.g., improperly washed food or spread from infected food-preparation staff), living in unsanitary conditions or from close personal contact, such as by caring for someone infected with the virus. Hepatitis A virus is remarkably stable; it can survive on surfaces for weeks, withstand freezing, and resist inactivation by some disinfectants. Standard alcohol hand sanitizers are less effective, so thorough handwashing with soap and water is critical and required to reduce spread.
People are most infectious in the one to two weeks prior to the onset of jaundice, when the amount of virus in their feces is at its peak. This means they may transmit the virus before realizing they are ill, contributing to more stealthy spread. Child care workers may be exposed to dirty diapers without knowing the child is infected, and food preparation workers with inadequate hand hygiene may prepare meals for many without being aware of their illness. Outbreaks have been traced to restaurants, child care centers, correctional facilities, and communities with limited sanitation.
Post-exposure prophylaxis with either hepatitis A vaccine or immune globulin is recommended for unvaccinated individuals who have been exposed in the past two weeks. The vaccine is generally preferred for healthy individuals 12 months through 40 years of age, while immune globulin is used in infants. Healthy adults over 40 can use vaccine or immune globulin. Those who are immunocompromised or have chronic liver disease should receive both.
Hepatitis A: Key clinical takeaways
Although hepatitis A is less common in the U.S. than in the past, outbreaks continue to occur, often in under-immunized adult populations. Providers should consider hepatitis A in patients with compatible illness, particularly if they have a history of recent travel, drug use, homelessness, or exposure to known outbreaks. Vaccination remains the most effective preventive measure and should be reviewed during both pediatric and adult visits.
Resources for families
- Hepatitis A: The Diseases & Vaccines (webpage)
- Vaccines on the Go: What You Should Know (mobile app)
- Why do Babies Get the Hepatitis A Vaccine? (video)