Wiedermann G, Ambrosch F, André F E, D'Hondt E, Delem A, Safary A
Institute for Specific Prophylaxis and Tropical Medicine, Vienna, Austria.
Vaccine. 1992;10 Suppl 1:S129-31. doi: 10.1016/0264-410x(92)90566-3.
A level of 10 mIU hepatitis A antibodies/ml as measured by ELISA is believed to be the minimal protective concentration. If this level is considered, the mean persistence of vaccine induced antibodies is approximately 10-11 years after booster dose, 6-7 years if only the primary doses are given and 5-6 years if the minimal individual titre is taken into account.