Did a bit of a search on the longevity of the Hep A and B vaccines. Seems like there is no fixed standard. 20 years or longer has been mentioned.
"In the United States, the incidence of hepatitis A virus (HAV) infection has been reduced through universal childhood vaccination. However, the duration of immunogenicity for the hepatitis A vaccine is not known. We report on the 22 year follow-up time point of a cohort of Alaska children who were randomized to three different vaccine schedules: A) 0, 1, and 2 months; B) 0, 1, and 6 months; and C) 0, 1, and 12 months. Among 46 participant available for follow-up, 40 (87%) maintained protective levels of anti-hepatitis A antibody. These results indicate that a supplemental booster dose is not yet necessary at or before the 22-year time point."
"Years ago, the standard 3-round Hepatitis B vaccine provided protection for up to seven years. However, today’s vaccines provide you with more than 20 years of protection.
This means that booster doses are largely unneeded these days. However, it is recommended for certain groups to take subsequent booster doses. At-risk groups include hemodialysis patients and other individuals with seriously compromised immune systems, such as people infected with HIV, chemotherapy patients, and recipients of hematopoietic stem-cell transplants."