Jürgen Kuball, MD, PhD, Utrecht University, Utrecht, Netherlands, talks on vaccine failure in allogeneic hematopoietic stem cell transplantation (alloHSCT) recipients. It has been demonstrated that patients who undergo alloHSCT often develop a suboptimal immune response to vaccines against COVID-19 and other diseases. Several predictive factors for vaccine failure including a poorly developed immune system can be used to guide vaccination decisions. Prof. Kuball recommends that alloHSCT recipients get vaccinated, but only 3-6 months after transplantation, and emphasizes the importance of checking the success of the vaccine. This interview took place at the EBMT-EHA 4th European CAR T-cell Meeting which was held virtually in 2022.