Immunogenicity and safety of the BNT162b2 mRNA COVID-19 vaccine in haematopoietic stem cell transplantation recipients.

The immunogenicity and safety of Pfizer-BioNTech BNT162b2 mRNA vaccine in allogeneic haematopoietic stem cell transplantation (HSCT) recipients are unknown. We prospectively followed 152 HSCT recipients who were at least six months following transplantation and with no active acute graft-versus-host disease (GVHD). Blood samples were taken 2-4 weeks after the second vaccination and analyzed for receptor-binding domain (RBD) antibodies and neutralizing antibodies (NA).