In the moderate/high groups, we found a significant correlation between anti-Spike Ab titers and changes in IFN-γ and IP-10/CXCL10 levels after the 1st vaccine dose, and between anti-Spike Ab titers and changes in IFN-γ and IL-15 levels after the 2nd vaccine dose, suggesting that the cytokine signature consisting of IFN-γ, IL-15, and IP-10/CXCL10 could serve as a biomarker of effective vaccination in vaccinated transplant patients with hematological malignancies, as previously reported for HCW (21). This evidence concerns the gene IL15 and hematologic disorder.