Timing of rejection events preceded by Covid-19 mRNA vaccination in recipients of solid organ transplants

Objectives: SARS-CoV-2 mRNA vaccine reactogenicity has raised concerns regarding the risk of rejection in solid organ transplant recipients. We explored whether SOT recipients diagnosed with acute rejection had previously received a vaccine injection within a timeframe consistent with a causal link. Methods: We identified all SOT recipients with a diagnosis of acute rejection from 2020 to 2022 and who had previously received a SARS-CoV-2 vaccination, and analysed whether the delay between vaccination and rejection was constant. Results: In the 45 identified patients, median delay between the last SARS-CoV-2 vaccination and the rejection was 102 days [IQR 48-178]; the continuous distribution of this delay, with no identifiable time pattern, is not in favor of a role of vaccination in rejection. Conclusion: SARS-CoV-2 mRNA vaccination is unlikely to trigger rejection in SOT recipients.