Key points
- Hepatitis A outbreaks can occur from different sources and spread through either foodborne or person-to-person transmission.
- State and jurisdictions typically lead outbreak investigations, but CDC can provide support anytime states or jurisdictions request it.
- When requested, CDC offers health departments support including gathering and monitoring case data, ensuring access to testing and vaccination, and providing information to health care professionals around the country, as well as the public, as needed.
What causes an outbreak
The most recent hepatitis A outbreaks have occurred from several different sources:
- Foodborne transmission through ingestion of contaminated food.
- Person-to-person transmission through close contact with a person infected with the virus, most recently among people who use drugs, people experiencing homelessness, and men who have sex with men.
Outbreaks in the United States
Hepatitis A declined dramatically after 1996 when health officials first recommended hepatitis A vaccine in the US.
In 2015, there were 1,390 reported cases of hepatitis A in the nation. The widespread outbreaks associated with person-to-person transmission started in 2016.
Since then, CDC has reported more than 44,000 cases nationwide. The outbreaks have caused severe health issues, putting many in the hospital and killing more than 400 people.
For a list of all recent hepatitis A outbreaks, see Hepatitis A Outbreaks.
What CDC and partners do to respond
State and local health departments typically lead the investigations of local outbreaks of hepatitis A. CDC can provide support any time states or jurisdictions request it, such as sending "disease detectives" to help local health officials trace an outbreak, or helping in other ways such as:
- Communicating with public health officials from states with reported cases and providing technical assistance.
- Gathering data reported by states on confirmed cases and evaluating and monitoring these data from a national perspective.
- Providing support on vaccine supply and distribution and vaccine response strategy development.
- Ensuring that affected areas have access to hepatitis A testing and vaccination.
- Testing clinical specimens from suspected hepatitis A cases when requested by states.
- Providing technical assistance and answering questions related to molecular and serologic laboratory testing.
- Providing rapid assistance on the ground during outbreak investigations, often through a formal request by the state health department.
- Alerting clinicians, health care facilities, and public health officials around the country about current outbreaks and providing vaccine policy and clinical guidance for health care providers.
- Providing information to public and health care providers through a variety of media.
What you can do
Understand your risk
Some groups of people have a higher risk of getting hepatitis A during outbreaks. Learn who is at higher risk for infection.
Get vaccinated
Hepatitis A vaccine is the best way to prevent HAV infection. Learn how to get vaccinated.
Practice good hand hygiene
Thoroughly wash your hands with soap and warm water to prevent the spread of many illnesses, including hepatitis A.
If you think you've been exposed
If you think you've been exposed to hepatitis A, contact a health professional as soon as possible.
Post-exposure prophylaxis
If you think you've been exposed to HAV and haven't previously received hepatitis A vaccine, talk to your doctor about a prevention measure called post-exposure prophylaxis (PEP). PEP should be administered as soon as possible within 2 weeks of exposure to HAV. This prevention measure includes hepatitis A vaccine, and, for some people, another medicine called immune globulin.
If you have been around someone diagnosed with hepatitis A and aren't sure whether you have had the vaccine, talk to your doctor right away. Getting treated within 2 weeks after exposure can prevent you from getting sick.