Persistence of antibody to Hepatitis A virus 20?years after receipt of Hepatitis A vaccine in Alaska

摘要

Summary Hepatitis A vaccine is recommended for children ≥1?year old to prevent hepatitis A virus ( HAV ) infection. However, the duration of vaccine‐induced immunity is unknown. We evaluated a cohort of Alaska Native persons 20?years after HAV vaccination. Children aged 3‐6?years had been previously randomized to receive three doses of HAV vaccine (360 ELISA units/dose) at: (i) 0,1,2?months; (ii) 0,1,6?months; and (iii) 0,1,12?months. We measured anti‐ HAV antibody concentrations every 2‐3?years; described geometric mean concentrations ( GMC ) and the proportion with protective antibody (≥20 mIU mL ‐1 ) over time; and modelled the change in GMC using fractional polynomial regression. Of the 144 participants, after 20?years 52 (36.1%) were available for the follow‐up (17, 18, 17 children in Groups A, B and C, respectively). Overall, 46 (88.5%) of 52 available participants had anti‐ HAV antibody concentrations ≥20 mIU mL ‐1 , and overall GMC was 107 mIU mL ‐1 . Although GMC levels were lower in Group A (60; CI 34‐104) than in Group B (110; CI 68‐177) or Group C (184; CI 98‐345) (B vs C: P =.168; A vs B/C: P =.011), there was no difference between groups after adjusting for peak antibody levels post‐vaccination ( P =.579). Models predicted geometric mean concentrations of 124 mIU mL ‐1 after 25?years, and 106 mIU mL ‐1 after 30?years. HAV vaccine provides protective antibody levels 20?years after childhood vaccination. Lower antibody levels in Group A may be explained by a lower initial peak response. Our results suggest a booster vaccine dose is unnecessary for at least 25‐30?years.