Cellular and humoral SARS-CoV2 vaccination responses in 192 adult recipients of allogeneic hematopoietic cell transplantation

Abstract To determine factors influencing the vaccination response against SARS-CoV2 is of importance in recipients of allogeneic hematopoietic cell transplantation (allo-HCT) as they display an increased mortality after SARS-CoV2 infection, an increased risk of extended viral persistence and reduced vaccination response. Real-life data on anti-SARS-CoV2-S1-IgG titres (n = 192) and IFN-γ release (n = 110) of allo-HCT recipients were obtained using commercially available, validated assays after vaccination with either mRNA (BNT™, Moderna™) or vector based vaccines (AstraZeneca™, Johnson/Johnson™) or after a heterologous protocol (vector/mRNA). Humoral response (78% response rate) was influenced by age, time after transplantation, the usage of ATG and ongoing immunosuppression, specifically corticosteroids. High counts of B cells during the vaccination period correlated with a humoral response. Only half (55%) of participants showed a cellular vaccination response. It depended on age, time after transplantation, ongoing immunosuppression with ciclosporin A, cGvHD and vaccination type with vector based protocols favoring response. Cellular response failure correlated with higher CD8 + count and activated/HLA-DR + T cells one year after transplantation. Our data provide the basis to assess both humoral and cellular responses after SARS-CoV2 vaccination in daily practice, thereby opening the possibility to identify patients at risk.