Researchers recently presented data indicating that the effectiveness of vaccines against SARS-CoV-2 may be reduced in patients with multiple myeloma (MM) or monoclonal gammopathy of undetermined significance (MGUS).
The study included 3,661 patients treated for MM at the national Veterans Affairs (VA) system in each of the prior 3 years; 818 vaccinated patients were matched with 818 who were not. In addition, 11,323 patients with MGUS were included; 4,798 who were vaccinated were matched with 4,798 who were not. In total, there was 11,232 patients, with a mean age of 73 years.
Among patients with MM, the estimated effectiveness of the vaccine was 9.7% from dose 1 to the end of the study, 12.6% from dose 2 to the end of the study, and 5.6% from 14 days after dose 2 to end of study.
Effectiveness improved in patients with MGUS but was still somewhat lower than in general population. In this group, the effectiveness was 28.4% from dose 1 to end of study, 34.1% from dose 2 to end of study, and 27.2% from 14 days after dose 2 to end of study. Among patients with MM who were vaccinated but not treated in the last 6 months, 2.6% of patients had breakthrough SARS-CoV-2 infection. The rate of breakthrough infection was 5.2% among patients with more recent treatment.
The researchers said that although vaccination is an effective strategy for preventing SARS-CoV-2, the effectiveness may be reduced in patients with MM, likely due to coexisting immunosuppression.
Future studies need to evaluate disease state, type/timing of therapy, and determine the role of post-vaccination serologies and booster vaccination.
