Naturally acquired hepatitis A antibodies after haematopoetic stem cell transplantation

Poor response to hepatitis A vaccination in hematopoietic stem cell transplant recipients

BACKGROUND

Hepatitis A virus (HAV) infection is highly prevalent in developing countries. In countries experiencing a shift from intermediate/high endemicity to low endemicity, the World Health Organization recommends the incorporation of HAV vaccine into the national vaccination calendar for children aged ≥1 year. Since HAV antibodies wane over time, most HSCT revaccination guidelines advise vaccination as optional, following the country recommendation. However, no study has evaluated the serological response to HAV vaccine in allogeneic HSCT recipients.

METHODS

We conducted a prospective study in 46 HSCT recipients who received two doses of inactivated HAV vaccine. Blood samples were taken before vaccination to determine HAV prevalence rates, and before and 4-6 weeks after the second dose. Specific anti-HAV antibodies were detected by a competitive commercial enzyme immune assay.

RESULTS

Patients received the first dose of vaccine at a median of 332.5 (120-4134) days after HSCT. Median absolute lymphocyte count at vaccination was 1947 (696-12 500)/mm³ . The seroprevalence rate was 93.5% at inclusion. Although safe and well tolerated, the serological response to HAV vaccine in susceptible patients was poor (33%), and no boost effect was observed in seropositive patients.

CONCLUSIONS

In areas with intermediate/high seroprevalence of HAV, serology should be recommended prior to referral to vaccination. The mechanisms of antibody interference and how to overcome T-cell function deficiency need to be better understood in transplant populations receiving HAV vaccine. Alternative schedules of HAV vaccination should be evaluated in prospective trials.

Seroprevalence of Hepatitis A Virus in Pediatric Patients with Hematologic Malignancies after Chemotherapy and Hematopoietic Cell Transplantation

This retrospective study was performed to determine the seroprevalence of hepatitis A virus (HAV) in children and adolescents with hematologic malignancies after the completion of chemotherapy and hematopoietic cell transplantation (HCT). Of 97 enrolled patients, 60 (61.9%) were seropositive for HAV. The seroprevalences in patients undergoing chemotherapy and HCT were 60.3% (41/68) and 65.5% (19/29), respectively (P = 0.628). No significant factors associated with seropositivity for HAV after chemotherapy and HCT were identified. Anti-HAV tests and HAV re-vaccinations can be considered in children and adolescents with underlying hematologic malignancies after chemotherapy and HCT based on the anti-HAV results.

Laboratory diagnosis of hepatitis A

The diagnostic gold standard for hepatitis A is the detection of anti-hepatitis A virus (HAV) IgM antibodies and the determination of total anti-HAV by enzyme immunoassay. However, detection of HAV RNA can be useful in the diagnosis of patients without specific antibodies for hepatitis A and for the monitoring of infection. Studies using real-time PCR have demonstrated that HAV RNA can be detected not only in feces, but also in serum and saliva samples earlier than detection of antibodies, and that viremia may be present for a much longer period than the convalescent phase of hepatitis A. Alternative samples have been proposed for diagnosis, epidemiological studies, investigation of outbreaks and selection of persons receptive to vaccination. Understanding the events of clinical course that take place during the hepatitis A infection may lead to more effective diagnosis.