IFNG and COVID-19: It is important to note that levels of IFN-γ in the study recipients who received a transplant from a donor who was either vaccinated or exposed to COVID-19 were significantly higher at all post-HCT time points (p = 0.0370 at +d30 post-HCT) than IFN-γ levels measured in healthy individuals before BNT162b2 mRNA COVID-19 vaccination.