*Purpose: The risk of de novo HBV infection in liver transplant recipients of Hepatitis B core antibody (HBcAb) positive donor organs is tempered by availability of antiviral therapy that can be utilized for prophylaxis and HBV vaccinations used to promote Hepatitis B surface antibody (HBsAb) positivity and presumed protection against de novo infection. Unfortunately the duration of prophylaxis necessary and durability of HBsAb immunity to prevent de novo HBV infection remain unknown. The aim of this study is to determine the rate of HBV infection after alteration or discontinuation of prophylactic antiviral therapy.

*Methods: This retrospective multi-site observational study spanned January 2014 through November 2020. Transplant recipients ≥ age 18 with a negative HBsAg at time of transplant who received an HBcAb positive graft between 1/1/2014 and 12/31/2019 were screened for inclusion. Patients lost to follow-up or deceased within one year of transplant were excluded. Per institutional protocol, patients with positive HBsAb could discontinue antiviral prophylaxis beyond 1 year post transplant.

*Results: This study included 65 patients who received antiviral prophylaxis with lamivudine, entecavir, or tenofovir disoproxil fumarate for at least one year. Patients negative for HBsAb one year following liver transplantation or in whom HBsAb was unavailable (n=43, 66%) continued antiviral therapy. One patient developed de novo HBV despite antiviral prophylaxis after entecavir was switched to lamivudine therapy. Of the patients with positive HBsAb assays one year following liver transplantation (n=22, 34%), ten patients (45%) stopped antiviral prophylaxis. Four of these ten patients (40%) developed de novo HBV infection with HBV DNA positivity between 10-27 months post antiviral discontinuation. Table 1 describes characteristics of the five patients with de novo HBV infection from HBcAb positive donor organs.

*Conclusions: De novo hepatitis B infection is an ongoing risk for patients receiving a liver transplant with an HBcAb positive graft, regardless of positive HBsAb assay. Lifelong prophylaxis with antiviral therapy should be strongly recommended.

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