Efficacy of SARS-CoV-2 vaccination in patients with monoclonal gammopathies: A cross sectional study

SARS-CoV-2 vaccination is the most effective strategy to protect individuals with haematologic malignancies against severe COVID-19, while eliciting limited vaccine responses. We charac-terized the humoral responses following 3 mo after mRNA-based vaccines in individuals at different plasma-cell disease stages: monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM), and multiple myeloma on first-line therapy (MM), compared with a healthy population. Plasma samples from uninfected MM patients showed lower SARS-CoV-2-specific antibody levels and neutralization capacity compared with MGUS, SMM, and healthy individuals. Importantly, COVID-19 recovered MM individuals presented significantly higher plasma neutralization capacity compared with their uninfected counterparts, highlighting that hybrid immunity elicit stronger immunity even in this immunocompromised population. No dif-ferences in the vaccine-induced humoral responses were observed between uninfected MGUS, SMM and healthy individuals. In con-clusion, MGUS and SMM patients could be SARS-CoV-2 vaccinated following the vaccine recommendations for the general pop-ulation, whereas a tailored monitoring of the vaccine-induced immune responses should be considered in uninfected MM patients.