From the US CDC faq for the general public about hepatitis A
“Transmission / Exposure
How is hepatitis A spread?
Hepatitis A usually spreads when a person unknowingly ingests the virus from objects, food, or drinks contaminated by small, undetected amounts of stool from an infected person. Hepatitis A can also spread from close personal contact with an infected person such as through sex or caring for someone who is ill.
Contamination of food (this can include frozen and undercooked food) by hepatitis A can happen at any point: growing, harvesting, processing, handling, and even after cooking. Contamination of food or water is more likely to occur in countries where hepatitis A is common and in areas where there are poor sanitary conditions or poor personal hygiene. In the United States, chlorination of water kills hepatitis A virus that enters the water supply. The Food and Drug Administration (FDA) routinely monitors natural bodies of water used for recreation for fecal contamination so there is no need for monitoring for hepatitis A virus specifically.
Who is at risk for hepatitis A?
Although anyone can get hepatitis A, in the United States, certain groups of people are at higher risk, such as:
People with direct contact with someone who has hepatitis A
Travelers to countries where hepatitis A is common
Men who have sexual contact with men
People who use drugs, both injection and non-injection drugs
Household members or caregivers of a recent adoptee from countries where hepatitis A is common
People with clotting factor disorders, such as hemophilia
People working with nonhuman primates
I think I have been exposed to hepatitis A. What should I do?
If you have any questions about potential exposure to hepatitis A, call your health professional or your local or state health department. If you were recently exposed to hepatitis A virus and have not been vaccinated against hepatitis A, you might benefit from an injection of either hepatitis A vaccine or immune globulin. However, the vaccine or immune globulin are only effective if given within the first 2 weeks after exposure. A health professional can decide what is best based on your age and overall health.
What is postexposure prophylaxis (PEP)?
Postexposure prophylaxis (PEP) refers to trying to prevent or treat a disease after an exposure. For hepatitis A, postexposure prophylaxis is an injection of either hepatitis A vaccine or immune globulin. However, the vaccine or immune globulin are only effective in preventing hepatitis A if given within the first 2 weeks after exposure.
If I have had hepatitis A in the past, can I get it again?
No. Once you recover from hepatitis A, you develop antibodies that protect you from the virus for life. An antibody is a substance found in the blood that the body produces in response to a virus. Antibodies protect the body from disease by attaching to the virus and destroying it.”