25 years in adults and 14–20 years in children.
How long does hepatitis A vaccine protect you? Estimates for long-term protection for fully vaccinat-ed people (i.e., full two-dose series) suggest that pro-tection from hepatitis A virus infection could last for at least 25 years in adults and at least 14–20 years in children.  1 Understand that hepatitis B vaccination-induced protective antibodies can last for up to 15 years, but appear to fall off over time. 2  Patients who were vaccinated 10 to 15 years ago, especially those who were vaccinated as children, may not be adequately protected.  A. I took the Hep A vaccine and then six months later took a booster and it supposedly lasts for life. But you have to get the booster. I read that Hep B vaccine is similar. Here's some more info that I pulled out of an article: Both the vaccines for hepatitis A and the vaccines for hepatitis B are highly effective. In studies of the four vaccines used for hepatitis A, nearly 100% of all adults who receive one develop protective levels of antibodies within one month of receiving a single dose. Results are similar for the hepatitis B vaccine, and experts estimate that both vaccines will give immunity for up to 20 or 30 years and possibly for life. 1 For healthy persons aged 12 months–40 years, single-antigen Hepatitis A vaccine at the age-appropriate dose is preferred to IG because of the vaccine’s advantages, including long-term protection and ease of administration, as well as the equivalent efficacy of vaccine to IG. Persons who have recently been exposed to HAV and who have not been vaccinated previously should be administered a single dose of single-antigen Hepatitis A vaccine or IG (0.02 mL/kg) as soon as possible, within 2 weeks after exposure. For infants born to HBsAg-positive mothers, postvaccination testing should be performed 1–2 months after completion of ≥3 doses of a licensed hepatitis B vaccine series (i.e., at age 9–18 months, generally at the next well-child visit). This vaccine cannot be administered at birth, before age 6 weeks, or after age 71 months. †. § Combined Hepatitis A and hepatitis B vaccine. This vaccine is recommended for persons aged ≥18 years who are at increased risk for both hepatitis B virus and Hepatitis A virus infections. Hepatitis A vaccination is recommended for all children at age 1 year, for persons who are at increased risk for infection, for persons who are at increased risk for complications from Hepatitis A, and for any person wishing to obtain immunity. Persons who have recently been exposed to HAV and who have not been vaccinated previously should be administered a single dose of single-antigen Hepatitis A vaccine or IG (0.02 mL/kg) as soon as possible, within 2 weeks after exposure. Vaccination with the full, two-dose series of Hepatitis A vaccine is the best way to prevent HAV infection. Hepatitis A vaccine has been licensed in the United States for use in persons 12 months of age and older. Persons who have recently been exposed to HAV and who have not been vaccinated previously should be administered a single dose of single-antigen Hepatitis A vaccine or IG (0.02 mL/kg) as soon as possible, within 2 weeks after exposure. Previously, Hepatitis A vaccination was recommended to be administered at least 2–4 weeks before departure to an area with intermediate or high rates of Hepatitis A. Travelers who were departing in less than 2 weeks were recommended to receive receive immune globulin (IG) for short-term protection. Persons who have recently been exposed to HAV and who have not been vaccinated previously should be administered a single dose of single-antigen Hepatitis A vaccine or IG (0.02 mL/kg) as soon as possible, within 2 weeks after exposure. One dose of a monovalent hepatitis A vaccine protects most healthy people aged 1–40 years and should be administered as soon as travel is considered. The monovalent vaccine series should be completed according to the licensed schedule for long-term protection. 
http://immunize.org/catg.d/p4204.pdf http://www.adepalma.com/medpage/HowLongHepatitisBVaccineEffectiveCMETeachingBrief.htm http://answers.webmd.com/answers/5000584/how-long-do-hepatitis-vaccines-last http://www.cdc.gov/hepatitis/HAV/HAVfaq.htm http://www.cdc.gov/hepatitis/HBV/HBVfaq.htm http://www.cdc.gov/hepatitis/HAV/HAVfaq.htm http://www.cdc.gov/hepatitis/HAV/HAVfaq.htm http://www.cdc.gov/hepatitis/HAV/HAVfaq.htm http://wwwnc.cdc.gov/travel/yellowbook/2012/chapter-3-infectious-diseases-related-to-travel/hepatitis-a.htm
how long are hepatitis a vaccines good for