Certain cancer patients at risk of COVID-19 vaccine failure

April 12, 2021

People with cancer that affects the blood, bone marrow or lymph nodes may be at elevated risk of COVID-19 vaccine failure, particularly those with chronic lymphocytic leukemia, according to new results from an analysis of patients at UPMC Hillman Cancer Center as reported in a news release.

The finding prompted University of Pittsburgh School of Medicine and UPMC clinician-scientists to issue a cautionary statement in the preprint journal medRxiv, urging such patients and those who interact with them to take the COVID-19 vaccines available, but to continue wearing masks and practicing social distancing, even after full vaccination. They simultaneously are pursuing peer-reviewed publication of the findings.

 “As we see more national guidance allowing for unmasked gatherings among vaccinated people, clinicians should counsel their immunocompromised patients about the possibility that COVID-19 vaccines may not fully protect them against SARS-CoV-2,” said senior author Ghady Haidar, MD, UPMC Transplant and Infectious Diseases Physician and Assistant Professor in Pittsburgh School of Medicine’s Department of Infectious Diseases. “Our results show that the odds of the vaccine producing an antibody response in people with hematologic malignancies are the equivalent of a coin flip.”

Haidar cautioned that a negative antibody test does not necessarily mean that the patient lacks protection from the virus.

Hematologic malignancies are a classification of non-solid tumor cancers, including leukemias, myelomas and lymphomas. These patients have a greater than 30% risk of death if they contract COVID-19 and often receive antibody-depleting therapies, which means they should be prioritized for COVID-19 vaccination. However, they were excluded from COVID-19 mRNA vaccine trials, so data on the vaccines’ effectiveness are nonexistent.

Approximately three weeks after their final vaccination, 67 patients with hematologic malignancies who had been vaccinated with either the Pfizer or Moderna COVID-19 two-dose vaccines had their blood tested. Haidar and his colleagues found that more than 46% of the participants had not produced antibodies against SARS-CoV-2.

Moreover, only three in 13 patients with chronic lymphocytic leukemia (CLL)—a slowly progressing cancer of the blood and bone marrow—produced measurable antibodies, even though 70% of them weren’t undergoing any form of cancer therapy.

The team did not find a link between cancer therapy and antibody levels to indicate why some of the patients did not mount an adequate immune response to the vaccine. As expected, however, older patients were less likely to produce antibodies compared to younger patients.

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