Pre-graft vaccination or infection do not decrease COVID-19 infections in recipients of allogeneic stem cell transplantation vaccinated and/or protected by immunotherapy after transplant.

The impact of pre-graft COVID-19 vaccinations in donor or recipient as well as pre-graft infection has been studied in 157 adults having received allogeneic stem cell transplantation (Allo-SCT) for various hematological diseases during the delta/omicron waves. We showed here that pre-Allo-SCT COVID-19 vaccination and/or infection do not provide more protection in patients receiving vaccine, immunotherapy or both after transplant. COVID-19 vaccination is and remains of crucial importance after Allo-SCT, reinforcing the recommendation to start COVID-19 vaccination as soon as the third month following the transplant.