Covid-19 Vaccine Response in Heart Transplant Recipients

Overview

Clinical studies indicate a decrease in vaccine efficacy in certain immunocompromised populations (kidney transplant recipients, patients undergoing chemotherapy). It was recently reported that only 18% to 49% of heart transplant recipients developed antibodies after 2 doses of BNT162b2 vaccine. Following the published results, it is currently recommended to use 3 doses in organ transplant recipients who have not contracted COVID-19 and 2 doses in those who have been infected. The effectiveness of this strategy is not yet sufficiently evaluated in heart transplant recipients. Moreover, the factors associated with the humoral and cellular response, the kinetics and durability of the humoral response, the occurrence of the cellular immune response and the tolerance of the vaccine are not well known in this population. To provide answers to these different questions, we set ourselves the objective of evaluating the humoral and cellular response to messenger RNA (mRNA) vaccines in heart transplant recipients followed at Bichat Hospital.

In order to evaluate the effectiveness and safety of currently adopted vaccination strategies in heart transplant recipients we intend to study the humoral and cellular responses to SARS-CoV-2 mRNA vaccines in heart transplant recipients followed at Bichat Hospital. All heart transplant recipients followed at Bichat Hospital will be invited to participate in this research. The vaccination schedule was 3 doses for the seronegative patients without documented infection, and 2 doses for patients who were seropositive or had a positive Reverse Transcriptase - Polymerase Chain Reaction (RT-PCR) test for SARS-CoV-2. Most patients were vaccinated at Bichat Hospital. Their vaccination schedule will be recovered. Some patients refused vaccination. Since the beginning of 2020, the transplant patients have benefited from systematic serological tests and RT-PCR testing of nasopharyngeal swabs in the event of symptoms suggestive of SARS-CoV-2 infection as part of routine care. The results of these tests will be retrieved from medical records retrospectively in order to investigate the kinetics and durability of the humoral response. Demographic and clinical data will be collected to determine the factors associated with vaccine response. In addition, a whole blood sample will be drawn at inclusion in order to evaluate cellular response. The patients will be also asked to answer a questionnaire regarding vaccine tolerance. The effectiveness of vaccination program will be assessed after 6-month follow-up based on the occurrence of SARS-CoV-2 infection, unscheduled medical consultation or hospitalization.