The central question is whether allo-hematopoietic cell transplantation (allo-HCT) recipients can develop protective immunity against COVID-19 upon vaccination. This question needs to be answered urgently and would help the hematologist to provide recommendation / best treatment for these patients. In this pilot project Cov-Allo, this important question will be addressed in a cohort in which allo-HCT recipients will be vaccinated with the mRNA available COVID-19 vaccine according to the Belgian vaccination program. The primary objective is to assess immune response after administration of COVID-19 mRNA Vaccine BNT162b2 (Comirnaty®; Pfizer-BioNTech) in a population of 50 patients allo-HCT recipients. This number is based on the availabilities of vaccines and eligible patients. Moreover, as the study is observational and exploratory, no sample size calculation could be provided for this study.
