CD38 and plasma cell myeloma: However, since there are no detailed data provided by Greenberger et al. regarding the kind of anti-myeloma treatment and remission status, we assume that the differences in terms of seronegativity rates could be based on smaller proportions of myeloma patients under active treatment, particularly anti-CD38-directed treatment, and possibly more myeloma patients in deep remission, as every single one of these factors is known to impact vaccination response.