Humoral Immune Response after anti-SARS-CoV-2 Vaccine "Booster" Dose in Patients with Monoclonal Gammopathy of Undetermined Significance (MGUS)

Monoclonal gammopathy of undetermined significance (MGUS) is a pre-malignant plasma cell disorder reported in approximately 3-4% of individuals aged > 50 years, characterized by a low risk (about 1% per year) of progression into “overt” myeloma or other lymphoproliferative diseases. It is usually asymptomatic, but a higher risk of deep venous thrombosis and infections, as well as immune dysregulation, have been reported. About this last point, considering that vaccination against SARS-CoV2 is the main strategy to prevent adverse outcome of COVID-19 (declared a pandemic by the World Health Organization in March 2020), the evaluation of humoral response to COVID-19 vaccines has gained increasing interest as valuable surrogate of vaccine effectiveness. In this field, several papers investigated antibody response to anti-SARS-CoV-2 vaccination in patients with hematological diseases; by contrast, few data are available about patients with MGUS. Terpos et al.