Background: The COVID-19 pandemic, caused by SARS-CoV-2 virus, has resulted in over 100,000 deaths MESHD in the United States. Our institution has treated over 2,000 COVID-19 patients during the pandemic in New York City. The pandemic directly impacted cancer patients and the organization of cancer care. Mount Sinai Hospital has a large and diverse multiple myeloma MESHD multiple myeloma HP (MM) population. Herein, we report the characteristics of COVID-19 infection MESHD and serological response in MM patients in a large tertiary care institution in New York. Methods: We performed a retrospective study on a cohort of 58 patients with a plasma SERO-cell disorder (54 MM, 4 smoldering MM) who developed COVID-19 between March 1, 2020 and April 30, 2020. We report epidemiological, clinical and laboratory characteristics including persistence of viral detection by polymerase chain reaction (PCR) and anti- SARS-CoV-2 antibody SERO testing, treatments initiated, and outcomes. Results: Of the 58 patients diagnosed with COVID-19, 36 were hospitalized and 22 were managed at home. The median age TRANS was 67 years; 52% of patients were male TRANS and 63% were non-white. Hypertension MESHD Hypertension HP (64%), hyperlipidemia MESHD hyperlipidemia HP (62%), obesity MESHD obesity HP (37%), diabetes mellitus MESHD diabetes mellitus HP (28%), chronic kidney disease HP kidney disease MESHD (24%) and lung disease MESHD (21%) were the most common comorbidities. In the total cohort, 14 patients (24%) died. Older age TRANS (>70 years), male TRANS sex, cardiovascular risk, and patients not in complete remission (CR) or stringent CR were significantly (p<0.05) associated with hospitalization. Among hospitalized patients, laboratory findings demonstrated elevation of traditional inflammatory markers (CRP, ferritin, D-dimer) and a significant (p<0.05) association between elevated inflammatory markers, severe hypogammaglobulinemia, non-white race, and mortality. Ninety-six percent (22/23) of patients developed antibodies to SARS-CoV-2 SERO at a median of 32 days after initial diagnosis. Median time to PCR negativity was 43 (range 19-68) days from initial positive PCR. Conclusions: Drug exposure and MM disease MESHD status at the time of contracting COVID-19 had no bearing on mortality. Mounting a severe inflammatory response to SARS-CoV-2 and severe hypogammaglobulinemia were associated with higher mortality. The majority of patients mounted an antibody SERO response to SARS-CoV-2. These findings pave a path to identification of vulnerable MM patients who need early intervention to improve outcome in future outbreaks of COVID-19.