In the CoVonly group receiving only the third booster dose of COVID-19 vaccine, we found, on 1 day (d1) post-immunization, a strong increase of the cytokines IL-15, IL-6, TNF-α and IFN-γ as well as of the chemokine CXCL10 (Figure 4A–E). This evidence concerns the gene IL15 and COVID-19.