Our findings confirmed that a third mRNA vaccine failed to warrant long-term humoral immune responses against SARS-CoV-2 in the setting of patients treated with high dose of dexamethasone or undergoing continuous MM treatment (with monoclonal antibodies alone or associated with other drugs) or reporting a low value of IgM, as reported by our working group in different hematological diseases (e.g., patients affected by myelofibrosis) (11). Here, CD40LG is linked to hematologic disorder.