Vaccinated multiple myeloma patients are more susceptible to SARS-CoV-2

In 2019, patients with a history of immunological problems or cancer are likely to be at a higher risk of developing severe coronavirus disease. (COVID-19). This is especially true for people with multiple myeloma (MM).

SARS-CoV-2 infections

In patients with MM and other hematological malignancies, recent studies have found a reduced rate of seroconversion after vaccination with messenger RNA (mRNA) anti-SARS-CoV-2 vaccines.

However, the risk and consequences of SARS-CoV-2 infection in MM patients who have been vaccinated are unknown.

Researchers recently published a study in JAMA comparing the risks of breakthrough infections in patients with MM and those without cancer after completing their immunization schedule.

Study details

Researchers accessed de-identified patient electronic health records (EHRs) from 63 health care institutions in the United States using the cloud-based TriNetX Analytics network technology. A total of 5,07,288 patients were included in the trial if they met the following criteria:

  1. had a recent medical encounter(s) with health care organizations since December 1, 2020;
  2. had documented evidence of full vaccination in the EHRs (Pfizer-BioNTech, Moderna, or Johnson & Johnson vaccine) between December 1, 2020, and October 8, 2021;
  3. and had no prior COVID-19 infection.

33.8 percent of 1,182 vaccinated MM patients had monoclonal gammopathy of unknown significance (MGUS), 11.7 percent were in remission, 88.7% had never achieved remission, 60.0 percent had chemotherapy, 50.3 had targeted therapy, 12.1 had radiation therapy, and 26.5 had stem cell transplant; mean (SD) blood lymphocyte count was 2.08 109 /L (12.2 109 /L).

34.8 had MGUS, 15.5 were in remission, 86.6 had never achieved remission, 64.2 had chemotherapy, 54.3 had targeted therapy, 11.2 had radiation therapy, and 27.8 had stem cell transplant among 187 patients with MM with SARS-CoV-2 breakthrough infections; mean (SD) blood lymphocytes count was 1.63 109 /L (2.01 109 /L).

In the MM population, the total risk of SARS-CoV-2 breakthrough infections was 15.4 percent, compared to 3.9 percent in the non-cancer population. Patients with MM remained at considerably higher risk for breakthrough infections after propensity score matching for demographics, unfavorable socioeconomic determinants of health, transplant procedures, comorbidities, vaccination types, and medications compared to matched patients without cancer (Hazard Ratio, 1.34). For patients with MM, the projected chance of hospitalization at the end of the time window (October 8, 2021) was 34.4.


Patients with MM were shown to have a higher chance of developing breakthrough infections and being admitted to the hospital, according to this study. These findings point to the need for improved mitigation techniques to be developed and implemented. More research into the timing and impact of vaccine boosters in such an immunocompromised group could also assist patients’ health outcomes.

Journal reference:

  • Wang, L., Berger, N. and Xu, R. (2021) “Risks of SARS-CoV-2 Breakthrough Infection and Hospitalization in Fully Vaccinated Patients With Multiple Myeloma”,¬†JAMA Network Open, 4(11), p. e2137575.¬†doi: 10.1001/jamanetworkopen.2021.37575