2709. Immune Response After Diphtheria and Tetanus Toxoid Booster in Patients with Adult-Onset Immunodeficiency with Anti-interferon-γ Autoantibody

Abstract Background Immunization were the key of prevention in tetanus and diphtherial disease. Nevertheless, in previous observational study, low seroprotection rate of both diphtheria and tetanus were observed in Thai healthy population. Reduced-dose diphtheria and tetanus toxoid vaccine (dT) was recommended to all adult patients regardless of immunologic status. However, data on vaccine efficacy in interferon gamma (IFN-γ) autoantibody were limited. We therefore conducted clinical study to evaluate efficacy and safety of one dose of dT in IFN-γ autoantibody patient compared with healthy individuals at 4 weeks after vaccination. Methods Study was conducted from February to April 2019. Total 18 patients with confirmed IFN-γ autoantibody were enrolled. Baseline tetanus and diphtheria serologic study and 4 weeks after vaccination were examined. Antibody levels were measured with a solid-phase IgG-specific ELISAs (EUROIMMUN, Germany). Geometric mean titers (GMTs) were calculated using the log transformation of serological titers and from taking the antilog mean of the transformed values. Results Seroprevalence of tetanus was 94.5% in healthy population compared with 60.1% in IFN-γ autoantibody patients. While, seroprevalence of diphtheria was 27.8% and 77.8%, respectively. After vaccination, all healthy adults had reached seroprotection level in both diphtheria and tetanus. For patients with IFN-γ autoantibody, 88.9% and 94.4% had anti-tetanus toxin IgG and anti-diphtheria toxin IgG level above 0.1 IU/mL, respectively. These results indicated seroconversion rate of 71% for tetanus and 75% for diphtheria after dT vaccination. (Table 2). In the subgroup analysis, unboosted IFN-γ autoantibody patient had lower tetanus seroconversion rate compared with previously boosted patient (50% vs 100%). Active infection was also associated with lower immune response after tetanus vaccination. There was no severe adverse event in both group. Conclusion This is the first study on immune response after dT vaccination in IFN-γ autoantibody patient. Seroconversion rate of dT vaccine in IFN-γ autoantibody patient were slightly lower than healthy adults. Active infection and previously unboosted patient provided lower immune response of tetanus. Disclosures All authors: No reported disclosures.