Abstract

Determinants of Hepatitis A Vaccine Immunity in a Cohort of Human Immunodeficiency Virus-Infected Children Living in Switzerland Pierre Alex Crisinel a , * , Klara Maria Posfay-Barbe a , Christoph Aebi b , Jean-Jacques Cheseaux c , Christian Kahlert d , Christoph Rudin e , David Nadal f and Claire-Anne Siegrist a , g the Swiss Mother and Child HIV Cohort Study of Switzerland (MoCHiV) a Department of Pediatrics, Geneva Medical School and University Hospitals of Geneva, Geneva, Switzerland b Department of Pediatrics and Institute for Infectious Diseases, University of Bern, Bern, Switzerland c Department of Pediatrics, University Hospital CHUV, Lausanne, Switzerland d Ostschweizer Kinderspital, St. Gallen, Switzerland e University Children's Hospital, Basel, Switzerland f Division of Infectious Diseases and Hospital Epidemiology, University Children's Hospital of Zurich, Zurich, Switzerland g Center for Vaccinology, Geneva Medical School and University Hospitals of Geneva, Geneva, Switzerland ABSTRACT Vaccination in HIV-infected children is often less effective than in healthy children. The goal of this study was to assess vaccine responses to hepatitis A virus (HAV) in HIV-infected children. Children of the Swiss Mother and Child HIV Cohort Study (MoCHiV) were enrolled prospectively. Recommendations for initial, catch-up, and additional HAV immunizations were based upon baseline antibody concentrations and vaccine history. HAV IgG was assessed by enzyme-linked immunosorbent assay (ELISA) with a protective cutoff value defined as ≥10 mIU/ml. Eighty-seven patients were included (median age, 11 years; range, 3.4 to 21.2 years). Forty-two patients were seropositive (48.3%) for HAV. Among 45 (51.7%) seronegative patients, 36 had not received any HAV vaccine dose and were considered naïve. Vaccine responses were assessed after the first dose in 29/35 naïve patients and after the second dose in 33/39 children (25 initially naïve patients, 4 seronegative patients, and 4 seropositive patients that had already received 1 dose of vaccine). Seroconversion was 86% after 1 dose and 97% after 2 doses, with a geometric mean concentration of 962 mIU/ml after the second dose. A baseline CD4 + T cell count below 750 cells/μl significantly reduced the post-2nd-dose response ( P = 0.005). Despite a high rate of seroconversion, patients with CD4 + T cell counts of <750/μl had lower anti-HAV antibody concentrations. This may translate into a shorter protection time. Hence, monitoring humoral immunity may be necessary to provide supplementary doses as needed.