Hepatitis A: The Disease & Vaccine
Have you ever gone into a restroom in a restaurant and seen the sign about employees washing their hands before returning to work? When you see those signs, think about hepatitis A virus. It is one of the main reasons for those signs. Hepatitis A virus spreads through food and water contaminated with feces from an infected person. If an infected restaurant worker doesn’t wash their hands well between using the restroom and returning to the kitchen, they can spread the virus to others.
Hepatitis A virus can also spread if food is grown in areas with low sanitation standards. For example, people can get hepatitis A from improperly washed or uncooked food. Recent U.S. outbreaks have been traced to onions, pomegranates, scallops, blackberries and strawberries.
Between 2016 and 2019, hepatitis A outbreaks in the U.S. increased due to the opioid epidemic. Lower levels of sanitation and crowding related to homelessness as well as use of shared drug paraphernalia contributed to these increases.
All these examples demonstrate why hepatitis A virus should not be classified only as a travel-related illness. Anyone can be infected with hepatitis A virus through common foods, like frozen berries, and common activities, like eating food prepared by someone else.
Each year, in the U.S. about 1,000-17,500 people are infected with hepatitis A virus. About 75 people die from their infection. Many of those infected are children. For these reasons, all children are recommended to get the hepatitis A vaccine between 12 and 23 months of age. Unvaccinated young people up to 18 years of age should also get hepatitis A vaccine.
The disease
What is hepatitis A virus?
Hepatitis A virus is hardy. This virus can survive outside of the body, such as in shellfish, water, soil and marine sediment. It can be killed by household cleaning agents, like bleach and toilet-cleaning chemicals that contain 23% hydrochloric acid.
Once a person has been naturally infected or vaccinated, they will not get hepatitis A again.
Hepatitis A virus causes inflammation of the liver, called hepatitis. Symptoms can include:
- Fever
- Yellowing of the skin or eyes, called jaundice
- Dark-colored urine
- Clay-colored bowel movements
- Tiredness
- Nausea and vomiting
Young children are much less likely to have symptoms when infected with hepatitis A virus compared with adults. But children can still spread the virus to others.
How do you catch hepatitis A virus?
Hepatitis A virus is found in the feces and blood of infected people. Feces from an infected person can contaminate food and water, including water used to wash food in countries with poor sanitation. This can spread the virus to other people in a number of ways, such as:
- Babies with hepatitis A virus will have diapers contaminated with the virus. Adults changing these diapers are likely to get infected if they don't carefully wash their hands with soap and water after handling diapers.
- Infected people working in the food industry who do not use proper handwashing techniques between using the restroom and handling food can spread the virus.
- People living with infected individuals can be exposed because of the likelihood of contact with feces in bathrooms or on clothing or other items. They can also be exposed from contaminated food, particularly if the infected person is preparing meals and has not washed their hands well after using the restroom.
- Countries or cities with low standards for handling and disposing of sewage more commonly have high levels of hepatitis A infections. The virus gets into the water supply and contaminates anything that comes in contact with the water, including food. It is probably realistic to think about a thin layer of hepatitis A virus covering anything you could put into your mouth in many developing countries.
Unfortunately, people infected with hepatitis A can spread the virus to others for up to two weeks before they have symptoms. As such, they may infect others before even knowing they have hepatitis A.
Cases of hepatitis A have also occurred following blood transfusions and organ transplants. The virus can also spread to babies passing through the birth canal during delivery, suggesting that the virus can sometimes be spread by blood. But spread from blood is much less common than spread from feces.
How can you avoid catching hepatitis A virus when traveling?
Anyone traveling to countries where hepatitis A virus infections are common should avoid the following:
- Ice and unbottled water
- Uncooked shellfish
- Uncooked or unpeeled fruits and vegetables
- Salads
- Food from street vendors
People who have not been vaccinated against hepatitis A should get the vaccine at least two weeks before traveling.
The vaccine
How is the hepatitis A vaccine made?
The hepatitis A vaccine is made by taking whole hepatitis A virus and killing it with the chemical formaldehyde. Because the virus is killed, or inactivated, it cannot cause hepatitis (see How Are Vaccines Made?).
Does the hepatitis A vaccine have side effects?
The hepatitis A vaccine can cause pain, redness and tenderness where the shot was given. The vaccine can also cause headache in about 5 of every 100 recipients.
The hepatitis A vaccine has been given to millions of people without serious side effects.
Who should get the hepatitis A vaccine?
The hepatitis A vaccine is recommended for all children between 12 months and 18 years of age living in the U.S.
It is also recommended for others at increased risk of infection, including:
- People traveling to countries with moderate or high rates of hepatitis A
- People in close contact with a child adopted from a country with moderate or high rates of hepatitis A
- People experiencing homelessness
- Men who have sex with men
- People who use injection or non-injection drugs
- People with chronic liver disease or HIV infection
- People with increased risk of exposure because of their job
- Pregnant women who might be at increased risk
- Unvaccinated people 1 year of age and older
- Unvaccinated people 1 year of age and older who have been exposed to hepatitis A in the last two weeks (known as postexposure prophylaxis).
The hepatitis A vaccine is typically given as a series of two shots. The second dose is given at least six months after the first. Children receiving the first dose should be at least 1 year old. Those up to 18 years old who have not been vaccinated against hepatitis A should get the vaccine.
Because hepatitis A outbreaks occur each year in the U.S., adults who wish to be protected against the disease can be vaccinated.
If an unvaccinated person 1 year of age or older is exposed to hepatitis A, they should get one dose of hepatitis A vaccine within two weeks of exposure. This is called postexposure prophylaxis. These people should get a second dose six months after the first dose for long-term protection.
Other questions you might have
Why did a 2021-22 hepatitis A outbreak in Virginia concern health officials?
On April 7, 2023, the CDC reported a hepatitis A outbreak in the journal Morbidity and Mortality Weekly Report (MMWR). The outbreak occurred in Virginia between September 2021 and September 2022. Several aspects of this outbreak were concerning:
- The first case was an infected restaurant worker with jobs at three locations, which resulted in 51 additional cases. More concerning to public health officials was evidence of sustained community transmission in the months that followed. This sustained spread in the community was unusual for hepatitis A and led to an additional 98 cases.
- Public health officials were unable to get information from more than half of the people with infections resulting from spread in the community. Their difficulties were from lack of contact information and one person refusing to share information.
- A few of the people exposed to the infected restaurant worker were at increased risk for severe disease due to factors like homelessness, drug use, male-to-male sexual contact, and incarceration. Yet, many of these people had more severe cases. More than 60% were hospitalized, three died, and one needed a liver transplant.
- A 2013 Substance Abuse and Mental Services Administration survey found that the restaurant industry had the highest rates of employees who reported using drugs in the previous month. While these data were not recent, they were concerning in this situation. One in 5 respondents working in the food industry reported using drugs, putting them at greater risk of hepatitis A infections. Given that the ongoing outbreak had started with an infected restaurant worker, it raised concerns about the possibility of larger or more frequent outbreaks.
- Fewer than 20% of the eligible employees were infected despite public health efforts to make vaccination convenient, including holding on-site vaccination clinics.
Given the number of people who dine out and the potential for unvaccinated, increased-risk food workers, a hepatitis A infection could easily affect any individual, family or community. While most people recover, not all do. And some people recover only after significant healthcare interventions. The Virginia situation in this report cost more than $3 million.
The hepatitis A vaccine can be used for any individual who wants protection against this infection. All patients and families should be aware of the opportunity for protection against hepatitis A virus.
What is hepatitis?
Hepatitis is a medical term used to describe inflammation of the liver. Because some viruses include the word “hepatitis” in their name, it is easy to be confused. Typically, an inflamed liver doesn’t work properly, leading to symptoms like:
- Nausea or vomiting
- Pain
- Dark-colored urine
- Light-colored bowel movements or diarrhea
- Joint pain
- Yellowing of the skin or the whites of the eyes (called jaundice)
However, because not everyone with hepatitis experiences symptoms, it is difficult to know whether some people actually have hepatitis.
Hepatitis can be caused by several viruses. Hepatitis A, hepatitis B, and hepatitis C may come to mind when one thinks about liver infections. There are also two less commonly known hepatitis viruses, called hepatitis D and hepatitis E. But hepatitis can be caused by other things as well, including:
- Adenovirus, cytomegalovirus, Epstein-Barr virus, herpes simplex virus, yellow fever virus and dengue virus
- Bacterial infections, particularly if they are severe enough to infect the bloodstream (called sepsis)
- Repeated consumption of large amounts of alcohol over time
- Chemicals, including poisons or medications
- Autoimmune disorders
- Genetic disorders, such as Wilson disease
- Dietary supplements
Liver inflammation can be short-lived or chronic. Chronic infections do not resolve and can lead to liver disease or liver cancer, such as can occur with hepatitis B infections.
Are infections caused by hepatitis A virus like those caused by hepatitis B virus?
Although hepatitis A virus sounds like it would be similar to hepatitis B virus, these infections are really quite different:
- Hepatitis B virus can cause long-term problems, such as cirrhosis (chronic liver damage) and liver cancer. On the other hand, hepatitis A virus doesn't cause long-term problems.
- Hepatitis B virus kills about 750 people every year in the U.S., whereas hepatitis A virus kills about 75 people every year.
- Hepatitis B virus is spread by contact with the blood of someone who is infected, but hepatitis A virus is typically spread in contaminated food or water.
How long should I wait after getting the hepatitis A vaccine before I travel?
The hepatitis A vaccine is most effective if given at least four weeks before traveling, but the vaccine is still somewhat effective if given at least two weeks before traveling.
Some people are recommended to get an antibody preparation, called immunoglobulin, if they are traveling within two weeks of their first dose of the hepatitis A vaccine. This includes:
- People 40 years of age and older
- People who are immunocompromised
- People with chronic liver disease
While people who receive immunoglobulin will not develop long-lived protection, the antibody preparation will help protect them during the trip. Protection from the immunoglobulin preparation lasts several months. The second dose of hepatitis A vaccine should be given 6 months after the first dose for long-term protection.
Why was the hepatitis A vaccine recommended for all children 2 to 18 years old after it was given to only certain groups at first?
When the hepatitis A vaccine first became available in the U.S., it was only recommended for people who were at increased risk for hepatitis A, including children living in communities with high rates of hepatitis A. This changed in 2006 when the recommendation was extended to include all infants between 12 months and 23 months of age. The recommendation was updated again in 2020 to include vaccination of all children between 2 and 18 years of age who were not previously vaccinated against hepatitis A.
Two factors shaped these recommendations:
- Early data: Originally, the vaccine could only be given to children 2 years of age or older. In 2006, following additional studies, use of the vaccine was expanded to include infants between 12 months and 23 months of age.
- Disease rates: Disease rates had been controlled in parts of the country where the vaccine was recommended, yet cases of hepatitis A were still occurring, particularly in regions where children were not regularly getting the vaccine. So, the recommendation was expanded to protect children in all parts of the country.
Relative risks and benefits
Do the benefits of the hepatitis A vaccine outweigh the risks?
Hepatitis A virus infections are quite common throughout the world. So common, in fact, that it is probably easier to list the countries where you are unlikely to catch the infection. In the U.S., between 1,000-17,500 cases of hepatitis A virus occur every year. Although hepatitis A virus infections do not cause long-term liver damage, about 75 people die every year from severe, overwhelming infections with this virus. Because the vaccine does not have serious side effects, the benefits of the hepatitis A vaccine clearly outweigh its risks.
Disease risks
- Inflammation of the liver
- Fever
- Vomiting
- Jaundice
- Nausea
Vaccine risks
- Pain, redness, and tenderness at the injection site
- Headache (5 of 100)
Reference
Orenstein WA, Offit PA, Edwards KM and Plotkin SA. Hepatitis A Vaccines in Plotkin’s Vaccines, 8th Edition. 2024, 365-388.
Reviewed by Paul A. Offit, MD, on April 8, 2026