Significant loss of hepatitis A Ab after allogeneic hematopoietic SCT in pediatric patients.

Loss of specific immunity after hematopoietic SCT (HSCT) is well documented for polio, measles, mumps and tetanus. There are limited studies reporting the loss of Hepatitis A virus immunity and no reports evaluating the effect of donor immunity on Hepatitis A virus (HAV) immunity loss after HSCT. A total of 49 of the 81 patients who received HSCT at the Ankara University Pediatric HSCT Unit from January 1997 to December 2006 had HAV serology tested before HSCT and were evaluated for seroprevalence, and 30 of 49 patients were evaluated for the loss of Ab and for the effect of donor immunity on the loss of HAV Abs. The seroprevalence before HSCT was 75.5%. Loss of Ab was detected in 43.5% (10/23) of the patients. The median time to loss of Ab was 12 months (12-32 months), and 60% of these patients were seronegative at 12 months after HSCT. After HSCT, 46.7% of the patients were seronegative. Loss of Ab was higher in the seronegative donor group (75 vs 26%). The loss of HAV Ab is high after allogeneic HSCT for pediatric patients. Reimmunization should be considered for the continuation of individual and community immunity. Further studies with larger study groups are warranted to clarify the role of donor immunity on the loss of HAV immunity.