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Shaji K. Kumar, MD

Prashant Kapoor, MD, FACP


Risk of Breakthrough COVID Infection After Vaccination in Patients With Hematologic Malignancies

By: Vanessa A. Carter, BS
Posted: Tuesday, September 6, 2022

Published as a Letter to the Editor in the Journal of Hematology & Oncology, Anthony Rooney, MD, of the University of Kansas Medical Center, Kansas City, and colleagues shared the findings of their study examining the rate of breakthrough SARS–CoV-2 infections among patients with hematologic malignancies who received two doses of an mRNA vaccine. Consequently, the researchers discovered that specifically individuals who had multiple myeloma or were on antineoplastic therapy at the time of vaccination were ultimately at higher risk of experiencing a breakthrough infection.

“Although the breakthrough infection rate in cancer patients during the observation period after two doses of an mRNA vaccine was low at 1.1%, infections were more severe with hospitalization and death rates of 27% and 5%, respectively,” stated the study authors, “highlighting the need for ongoing infection prevention and vigilance among this population.”

The investigators focused on 9,417 patients with solid tumors or hematologic malignancies who were queried from the University of Kansas Cancer Center Curated Cancer Clinical Outcomes Database. Participants treated with antineoplastic therapy underwent nasopharyngeal real-time polymerase chain reaction (RT-PCR) SARS–CoV-2 testing before each treatment cycle; those not on therapy underwent testing if they screened positive for COVID symptoms. Of note, a breakthrough infection was defined as a positive RT-PCR swab more than 14 days after the completion of two vaccine doses.

The median patient age was 67 years, with 15.8% and 8.9% of participants receiving antineoplastic therapy during the observation period and at the time of vaccination, respectively. With a median time to breakthrough infection of 144 days, 51% of individuals had symptoms without hospitalization, and 16% remained asymptomatic. In addition, patients with hematologic malignancies experienced breakthrough infections more frequently than those with solid tumors (relative risk [RR] = 1.63). And participants with multiple myeloma demonstrated the highest rate of breakthrough infection (RR = 2.96), and those with breast cancer had the lowest rate when compared with the other groups (RR = 0.51).

Disclosure: The study authors reported no conflicts of interest.

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