Impact of the Immune System on Response to Anti-Coronavirus Disease 19 (COVID-19) Vaccine in Allogeneic Stem Cell Recipients (Covid Vaccin Allo)

Impact of the Immune System on Response to COVID-19 Vaccine in Allogeneic Stem Cell Recipients (Covid Vaccin Allo)

The present study is a prospective phase IV study. All participants will receive the anti-Coronavirus Disease 2019 (COVID-19) Vaccine (messenger Ribonucleic acid-based vaccine, BNT162b2 or Comirnaty®, commercialized by Pfizer-BioNTech) being authorized in the European Union since December 2020. The vaccine is administered intramuscularly after dilution as a series of two doses at least 21 days apart.

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.

Inclusion Criteria:

• prior allogeneic hematopoietic stem cell transplantation 3 months to 5 years earlier (any donor type)
• age > or = 18 years at inclusion.
• written informed consent

Exclusion Criteria:

• HIV seropositivity
• Pregnancy
• Active malignant disease at inclusion
• Current grade III-IV acute Graft Versus Host Disease (GVHD)
• In vitro T-cell depletion of the graft if vaccination within the 6 months after transplantation.
• Rituximab administration in the 6 months prior to study inclusion
• Prior documented COVID-19 infection