LAUSR

Patients with multiple myeloma (MM) are at increased risk of infection and severe outcomes from COVID-19 infection, 1,2 partly owing to inadequate protection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. 2-7 Their sus-ceptibility stems from both immune-suppressive treatments used for MM and underlying immune-de fi ciency from the disease itself. 4,6,8 However, it is unknown how much risk is shared by patients with monoclonal gammopathy of undetermined signi fi cance (MGUS), 9,10 a precursor state to MM that does not require immune-suppressive treatment but may be associated with immune-de fi ciency. Here, we measured the risk of breakthrough infections among vaccinated patients with MM or MGUS relative to the patients without MM or MGUS in the national