Systems vaccinology identifies clinical and immunological correlates of SARS-CoV-2 vaccine response in solid-organ transplant recipients

Solid organ transplant (SOT) recipients are at enhanced risk of adverse outcomes following infectious challenges due to immunosuppressive treatment and additional comorbidities. Unfortunately, SOT recipients are also poor responders to the key medical intervention to preventing infection: vaccines. Here we performed a systems vaccinology study on a cohort of 59 kidney transplant recipients and 31 lung transplant recipients who received the mRNA Pfizer-BioNTech COVID-19 vaccine. Analyzing the immunological status of the patients prior to vaccination, we were able to identify multiple immunological associates of relatively improved vaccine responses following two or three doses of mRNA-based SARS-CoV-2 vaccine. These immunological associates predicted, with 95.0% and 93.3% accuracy, vaccine response after the second and third dose, respectively. Comparison of the immunological associates with vaccine response in SOT recipients revealed two distinct immune configurations: a non-classical configuration, distinct from the immune state of healthy subjects, associated with responses to two doses of mRNA vaccine and that could be mediated partly by the presence of double negative B cell subsets which are more prominently represented in responsive SOT recipients, and a “normalized” configuration, closer to the immune state of healthy subjects, associated with potent antibody responses to three doses of mRNA vaccine. These results suggest that immunosuppression in SOT recipients can result in distinct immune states associated with different trade-offs in vaccine responsiveness. Immune phenotyping of SOT recipients for immune constellation may be an effective approach for identifying patients most at risk of poor vaccine responses and susceptibility to vaccine-preventable diseases.